Merge branch 'development' into fix/instant/signature-denied

* development: (914 commits)
  Unfix compiler version except for top level contracts
  Move OrderValidator to extensions
  Update CHANGELOG
  Remove assembly version of matchOrders
  Add getOrderInfo check before calling fillOrder
  Update comments and hard code function selector constants
  Fix build after rebase
  update comments
  Fix build and add back tests
  Update dependency paths
  Add OrderMatcher tests
  feat: Add OrderMatcher contract that takes spread in multiple assets by calling `matchOrders` followed by `fillOrder`
  Update CHANGELOG
  Use more efficient equality checks
  Add note about input validation
  Use more efficient check for overflow
  Check if amount == 0 before doing division
  Reapply prettier
  New relayers
  feat(sra_client.py): Test deployed pkg via tox
  ...

17 files changed, 315 insertions, 117 deletions

diff --git a/packages/instant/.production.discharge.json b/packages/instant/.production.discharge.json
index 1ce39fdd8..c87f8b187 100644
--- a/packages/instant/.production.discharge.json
+++ b/packages/instant/.production.discharge.json
@@ -1,5 +1,5 @@
 {
-    "domain": "instant.0xproject.com",
+    "domain": "instant.0x.org",
     "build_command": "dotenv yarn build -- --env.discharge_target=production",
     "upload_directory": "umd",
     "index_key": "instant.js",
diff --git a/packages/instant/src/components/instant_heading.tsx b/packages/instant/src/components/instant_heading.tsx
index 816cc5c33..5b1f9592d 100644
--- a/packages/instant/src/components/instant_heading.tsx
+++ b/packages/instant/src/components/instant_heading.tsx
@@ -113,20 +113,23 @@ export class InstantHeading extends React.Component<InstantHeadingProps, {}> {
     }
 
     private readonly _renderEthAmount = (): React.ReactNode => {
+        const ethAmount = format.ethBaseUnitAmount(
+            this.props.totalEthBaseUnitAmount,
+            4,
+            <AmountPlaceholder isPulsating={false} color={PLACEHOLDER_COLOR} />,
+        );
+
+        const fontSize = _.isString(ethAmount) && ethAmount.length >= 13 ? '14px' : '16px';
         return (
             <Text
-                fontSize="16px"
+                fontSize={fontSize}
                 textAlign="right"
                 width="100%"
                 fontColor={ColorOption.white}
                 fontWeight={500}
                 noWrap={true}
             >
-                {format.ethBaseUnitAmount(
-                    this.props.totalEthBaseUnitAmount,
-                    4,
-                    <AmountPlaceholder isPulsating={false} color={PLACEHOLDER_COLOR} />,
-                )}
+                {ethAmount}
             </Text>
         );
     };
diff --git a/packages/instant/src/components/order_details.tsx b/packages/instant/src/components/order_details.tsx
index a8e0e2513..9c10ef9e6 100644
--- a/packages/instant/src/components/order_details.tsx
+++ b/packages/instant/src/components/order_details.tsx
@@ -4,124 +4,227 @@ import * as _ from 'lodash';
 import * as React from 'react';
 import { oc } from 'ts-optchain';
 
-import { BIG_NUMBER_ZERO } from '../constants';
+import { BIG_NUMBER_ZERO, DEFAULT_UNKOWN_ASSET_NAME } from '../constants';
 import { ColorOption } from '../style/theme';
+import { BaseCurrency } from '../types';
 import { format } from '../util/format';
 
 import { AmountPlaceholder } from './amount_placeholder';
+import { SectionHeader } from './section_header';
 
 import { Container } from './ui/container';
 import { Flex } from './ui/flex';
-import { Text } from './ui/text';
+import { Text, TextProps } from './ui/text';
 
 export interface OrderDetailsProps {
     buyQuoteInfo?: BuyQuoteInfo;
     selectedAssetUnitAmount?: BigNumber;
     ethUsdPrice?: BigNumber;
     isLoading: boolean;
+    assetName?: string;
+    baseCurrency: BaseCurrency;
+    onBaseCurrencySwitchEth: () => void;
+    onBaseCurrencySwitchUsd: () => void;
 }
 export class OrderDetails extends React.Component<OrderDetailsProps> {
     public render(): React.ReactNode {
-        const { buyQuoteInfo, ethUsdPrice, selectedAssetUnitAmount } = this.props;
-        const buyQuoteAccessor = oc(buyQuoteInfo);
-        const assetEthBaseUnitAmount = buyQuoteAccessor.assetEthAmount();
-        const feeEthBaseUnitAmount = buyQuoteAccessor.feeEthAmount();
-        const totalEthBaseUnitAmount = buyQuoteAccessor.totalEthAmount();
-        const pricePerTokenEth =
-            !_.isUndefined(assetEthBaseUnitAmount) &&
-            !_.isUndefined(selectedAssetUnitAmount) &&
-            !selectedAssetUnitAmount.eq(BIG_NUMBER_ZERO)
-                ? assetEthBaseUnitAmount.div(selectedAssetUnitAmount).ceil()
-                : undefined;
+        const shouldShowUsdError = this.props.baseCurrency === BaseCurrency.USD && this._hadErrorFetchingUsdPrice();
         return (
             <Container width="100%" flexGrow={1} padding="20px 20px 0px 20px">
-                <Container marginBottom="10px">
-                    <Text
-                        letterSpacing="1px"
-                        fontColor={ColorOption.primaryColor}
-                        fontWeight={600}
-                        textTransform="uppercase"
-                        fontSize="14px"
-                    >
-                        Order Details
-                    </Text>
-                </Container>
-                <EthAmountRow
-                    rowLabel="Token Price"
-                    ethAmount={pricePerTokenEth}
-                    ethUsdPrice={ethUsdPrice}
-                    isLoading={this.props.isLoading}
+                <Container marginBottom="10px">{this._renderHeader()}</Container>
+                {shouldShowUsdError ? this._renderErrorFetchingUsdPrice() : this._renderRows()}
+            </Container>
+        );
+    }
+
+    private _renderRows(): React.ReactNode {
+        const { buyQuoteInfo } = this.props;
+        return (
+            <React.Fragment>
+                <OrderDetailsRow
+                    labelText={this._assetAmountLabel()}
+                    primaryValue={this._displayAmountOrPlaceholder(buyQuoteInfo && buyQuoteInfo.assetEthAmount)}
                 />
-                <EthAmountRow
-                    rowLabel="Fee"
-                    ethAmount={feeEthBaseUnitAmount}
-                    ethUsdPrice={ethUsdPrice}
-                    isLoading={this.props.isLoading}
+                <OrderDetailsRow
+                    labelText="Fee"
+                    primaryValue={this._displayAmountOrPlaceholder(buyQuoteInfo && buyQuoteInfo.feeEthAmount)}
                 />
-                <EthAmountRow
-                    rowLabel="Total Cost"
-                    ethAmount={totalEthBaseUnitAmount}
-                    ethUsdPrice={ethUsdPrice}
-                    shouldEmphasize={true}
-                    isLoading={this.props.isLoading}
+                <OrderDetailsRow
+                    labelText="Total Cost"
+                    isLabelBold={true}
+                    primaryValue={this._displayAmountOrPlaceholder(buyQuoteInfo && buyQuoteInfo.totalEthAmount)}
+                    isPrimaryValueBold={true}
+                    secondaryValue={this._totalCostSecondaryValue()}
                 />
-            </Container>
+            </React.Fragment>
         );
     }
-}
 
-export interface EthAmountRowProps {
-    rowLabel: string;
-    ethAmount?: BigNumber;
-    isEthAmountInBaseUnits?: boolean;
-    ethUsdPrice?: BigNumber;
-    shouldEmphasize?: boolean;
-    isLoading: boolean;
+    private _renderErrorFetchingUsdPrice(): React.ReactNode {
+        return (
+            <Text>
+                There was an error fetching the USD price.
+                <Text
+                    onClick={this.props.onBaseCurrencySwitchEth}
+                    fontWeight={700}
+                    fontColor={ColorOption.primaryColor}
+                >
+                    Click here
+                </Text>
+                {' to view ETH prices'}
+            </Text>
+        );
+    }
+
+    private _hadErrorFetchingUsdPrice(): boolean {
+        return this.props.ethUsdPrice ? this.props.ethUsdPrice.equals(BIG_NUMBER_ZERO) : false;
+    }
+
+    private _totalCostSecondaryValue(): React.ReactNode {
+        const secondaryCurrency = this.props.baseCurrency === BaseCurrency.USD ? BaseCurrency.ETH : BaseCurrency.USD;
+
+        const canDisplayCurrency =
+            secondaryCurrency === BaseCurrency.ETH ||
+            (secondaryCurrency === BaseCurrency.USD && this.props.ethUsdPrice && !this._hadErrorFetchingUsdPrice());
+
+        if (this.props.buyQuoteInfo && canDisplayCurrency) {
+            return this._displayAmount(secondaryCurrency, this.props.buyQuoteInfo.totalEthAmount);
+        } else {
+            return undefined;
+        }
+    }
+
+    private _displayAmountOrPlaceholder(weiAmount?: BigNumber): React.ReactNode {
+        const { baseCurrency, isLoading } = this.props;
+
+        if (_.isUndefined(weiAmount)) {
+            return (
+                <Container opacity={0.5}>
+                    <AmountPlaceholder color={ColorOption.lightGrey} isPulsating={isLoading} />
+                </Container>
+            );
+        }
+
+        return this._displayAmount(baseCurrency, weiAmount);
+    }
+
+    private _displayAmount(currency: BaseCurrency, weiAmount: BigNumber): React.ReactNode {
+        switch (currency) {
+            case BaseCurrency.USD:
+                return format.ethBaseUnitAmountInUsd(weiAmount, this.props.ethUsdPrice, 2, '');
+            case BaseCurrency.ETH:
+                return format.ethBaseUnitAmount(weiAmount, 4, '');
+        }
+    }
+
+    private _assetAmountLabel(): React.ReactNode {
+        const { assetName, baseCurrency } = this.props;
+        const numTokens = this.props.selectedAssetUnitAmount;
+
+        // Display as 0 if we have a selected asset
+        const displayNumTokens =
+            assetName && assetName !== DEFAULT_UNKOWN_ASSET_NAME && _.isUndefined(numTokens)
+                ? new BigNumber(0)
+                : numTokens;
+        if (!_.isUndefined(displayNumTokens)) {
+            let numTokensWithSymbol: React.ReactNode = displayNumTokens.toString();
+            if (assetName) {
+                numTokensWithSymbol += ` ${assetName}`;
+            }
+            const pricePerTokenWei = this._pricePerTokenWei();
+            if (pricePerTokenWei) {
+                const atPriceDisplay = (
+                    <Text fontColor={ColorOption.lightGrey}>
+                        @ {this._displayAmount(baseCurrency, pricePerTokenWei)}
+                    </Text>
+                );
+                numTokensWithSymbol = (
+                    <React.Fragment>
+                        {numTokensWithSymbol} {atPriceDisplay}
+                    </React.Fragment>
+                );
+            }
+            return numTokensWithSymbol;
+        }
+        return 'Token Amount';
+    }
+
+    private _pricePerTokenWei(): BigNumber | undefined {
+        const buyQuoteAccessor = oc(this.props.buyQuoteInfo);
+        const assetTotalInWei = buyQuoteAccessor.assetEthAmount();
+        const selectedAssetUnitAmount = this.props.selectedAssetUnitAmount;
+        return !_.isUndefined(assetTotalInWei) &&
+            !_.isUndefined(selectedAssetUnitAmount) &&
+            !selectedAssetUnitAmount.eq(BIG_NUMBER_ZERO)
+            ? assetTotalInWei.div(selectedAssetUnitAmount).ceil()
+            : undefined;
+    }
+
+    private _baseCurrencyChoice(choice: BaseCurrency): React.ReactNode {
+        const onClick =
+            choice === BaseCurrency.ETH ? this.props.onBaseCurrencySwitchEth : this.props.onBaseCurrencySwitchUsd;
+        const isSelected = this.props.baseCurrency === choice;
+
+        const textStyle: TextProps = { onClick, fontSize: '12px' };
+        if (isSelected) {
+            textStyle.fontColor = ColorOption.primaryColor;
+            textStyle.fontWeight = 700;
+        } else {
+            textStyle.fontColor = ColorOption.lightGrey;
+        }
+        return <Text {...textStyle}>{choice}</Text>;
+    }
+
+    private _renderHeader(): React.ReactNode {
+        return (
+            <Flex justify="space-between">
+                <SectionHeader>Order Details</SectionHeader>
+                <Container>
+                    {this._baseCurrencyChoice(BaseCurrency.ETH)}
+                    <Container marginLeft="5px" marginRight="5px" display="inline">
+                        <Text fontSize="12px" fontColor={ColorOption.feintGrey}>
+                            /
+                        </Text>
+                    </Container>
+                    {this._baseCurrencyChoice(BaseCurrency.USD)}
+                </Container>
+            </Flex>
+        );
+    }
 }
 
-export class EthAmountRow extends React.Component<EthAmountRowProps> {
-    public static defaultProps = {
-        shouldEmphasize: false,
-        isEthAmountInBaseUnits: true,
-    };
+export interface OrderDetailsRowProps {
+    labelText: React.ReactNode;
+    isLabelBold?: boolean;
+    isPrimaryValueBold?: boolean;
+    primaryValue: React.ReactNode;
+    secondaryValue?: React.ReactNode;
+}
+export class OrderDetailsRow extends React.Component<OrderDetailsRowProps, {}> {
     public render(): React.ReactNode {
-        const { rowLabel, ethAmount, isEthAmountInBaseUnits, shouldEmphasize, isLoading } = this.props;
-
-        const fontWeight = shouldEmphasize ? 700 : 400;
-        const ethFormatter = isEthAmountInBaseUnits ? format.ethBaseUnitAmount : format.ethUnitAmount;
         return (
             <Container padding="10px 0px" borderTop="1px dashed" borderColor={ColorOption.feintGrey}>
                 <Flex justify="space-between">
-                    <Text fontWeight={fontWeight} fontColor={ColorOption.grey}>
-                        {rowLabel}
+                    <Text fontWeight={this.props.isLabelBold ? 700 : 400} fontColor={ColorOption.grey}>
+                        {this.props.labelText}
                     </Text>
-                    <Container>
-                        {this._renderUsdSection()}
-                        <Text fontWeight={fontWeight} fontColor={ColorOption.grey}>
-                            {ethFormatter(
-                                ethAmount,
-                                4,
-                                <Container opacity={0.5}>
-                                    <AmountPlaceholder color={ColorOption.lightGrey} isPulsating={isLoading} />
-                                </Container>,
-                            )}
-                        </Text>
-                    </Container>
+                    <Container>{this._renderValues()}</Container>
                 </Flex>
             </Container>
         );
     }
-    private _renderUsdSection(): React.ReactNode {
-        const usdFormatter = this.props.isEthAmountInBaseUnits
-            ? format.ethBaseUnitAmountInUsd
-            : format.ethUnitAmountInUsd;
-        const shouldHideUsdPriceSection = _.isUndefined(this.props.ethUsdPrice) || _.isUndefined(this.props.ethAmount);
-        return shouldHideUsdPriceSection ? null : (
+
+    private _renderValues(): React.ReactNode {
+        const secondaryValueNode: React.ReactNode = this.props.secondaryValue && (
             <Container marginRight="3px" display="inline-block">
-                <Text fontColor={ColorOption.lightGrey}>
-                    ({usdFormatter(this.props.ethAmount, this.props.ethUsdPrice)})
-                </Text>
+                <Text fontColor={ColorOption.lightGrey}>({this.props.secondaryValue})</Text>
             </Container>
         );
+        return (
+            <React.Fragment>
+                {secondaryValueNode}
+                <Text fontWeight={this.props.isPrimaryValueBold ? 700 : 400}>{this.props.primaryValue}</Text>
+            </React.Fragment>
+        );
     }
 }
diff --git a/packages/instant/src/components/payment_method.tsx b/packages/instant/src/components/payment_method.tsx
index 7c93f1d1c..abadf4bd6 100644
--- a/packages/instant/src/components/payment_method.tsx
+++ b/packages/instant/src/components/payment_method.tsx
@@ -8,6 +8,7 @@ import { envUtil } from '../util/env';
 import { CoinbaseWalletLogo } from './coinbase_wallet_logo';
 import { MetaMaskLogo } from './meta_mask_logo';
 import { PaymentMethodDropdown } from './payment_method_dropdown';
+import { SectionHeader } from './section_header';
 import { Circle } from './ui/circle';
 import { Container } from './ui/container';
 import { Flex } from './ui/flex';
@@ -29,15 +30,7 @@ export class PaymentMethod extends React.Component<PaymentMethodProps> {
             <Container width="100%" height="120px" padding="20px 20px 0px 20px">
                 <Container marginBottom="12px">
                     <Flex justify="space-between">
-                        <Text
-                            letterSpacing="1px"
-                            fontColor={ColorOption.primaryColor}
-                            fontWeight={600}
-                            textTransform="uppercase"
-                            fontSize="14px"
-                        >
-                            {this._renderTitleText()}
-                        </Text>
+                        <SectionHeader>{this._renderTitleText()}</SectionHeader>
                         {this._renderTitleLabel()}
                     </Flex>
                 </Container>
diff --git a/packages/instant/src/components/section_header.tsx b/packages/instant/src/components/section_header.tsx
new file mode 100644
index 000000000..d0974ebdc
--- /dev/null
+++ b/packages/instant/src/components/section_header.tsx
@@ -0,0 +1,20 @@
+import * as React from 'react';
+
+import { ColorOption } from '../style/theme';
+
+import { Text } from './ui/text';
+
+export interface SectionHeaderProps {}
+export const SectionHeader: React.StatelessComponent<SectionHeaderProps> = props => {
+    return (
+        <Text
+            letterSpacing="1px"
+            fontColor={ColorOption.primaryColor}
+            fontWeight={600}
+            textTransform="uppercase"
+            fontSize="12px"
+        >
+            {props.children}
+        </Text>
+    );
+};
diff --git a/packages/instant/src/components/zero_ex_instant_provider.tsx b/packages/instant/src/components/zero_ex_instant_provider.tsx
index 204115fa9..2de327cd7 100644
--- a/packages/instant/src/components/zero_ex_instant_provider.tsx
+++ b/packages/instant/src/components/zero_ex_instant_provider.tsx
@@ -122,6 +122,7 @@ export class ZeroExInstantProvider extends React.Component<ZeroExInstantProvider
                 window,
                 state.selectedAsset,
                 this.props.affiliateInfo,
+                state.baseCurrency,
             ),
         );
         analytics.trackInstantOpened();
diff --git a/packages/instant/src/constants.ts b/packages/instant/src/constants.ts
index 6d3680dc1..22f0cb6a4 100644
--- a/packages/instant/src/constants.ts
+++ b/packages/instant/src/constants.ts
@@ -17,6 +17,7 @@ export const ONE_MINUTE_MS = ONE_SECOND_MS * 60;
 export const GIT_SHA = process.env.GIT_SHA;
 export const NODE_ENV = process.env.NODE_ENV;
 export const NPM_PACKAGE_VERSION = process.env.NPM_PACKAGE_VERSION;
+export const DEFAULT_UNKOWN_ASSET_NAME = '???';
 export const ACCOUNT_UPDATE_INTERVAL_TIME_MS = ONE_SECOND_MS * 5;
 export const BUY_QUOTE_UPDATE_INTERVAL_TIME_MS = ONE_SECOND_MS * 15;
 export const DEFAULT_GAS_PRICE = GWEI_IN_WEI.mul(6);
diff --git a/packages/instant/src/containers/latest_buy_quote_order_details.ts b/packages/instant/src/containers/latest_buy_quote_order_details.ts
index 5dfe535e7..148735c47 100644
--- a/packages/instant/src/containers/latest_buy_quote_order_details.ts
+++ b/packages/instant/src/containers/latest_buy_quote_order_details.ts
@@ -1,32 +1,41 @@
-import { BuyQuoteInfo } from '@0x/asset-buyer';
-import { BigNumber } from '@0x/utils';
 import * as _ from 'lodash';
 import * as React from 'react';
 import { connect } from 'react-redux';
+import { Dispatch } from 'redux';
 import { oc } from 'ts-optchain';
 
+import { Action, actions } from '../redux/actions';
 import { State } from '../redux/reducer';
 
-import { OrderDetails } from '../components/order_details';
-import { AsyncProcessState } from '../types';
+import { OrderDetails, OrderDetailsProps } from '../components/order_details';
+import { AsyncProcessState, BaseCurrency, Omit } from '../types';
+import { assetUtils } from '../util/asset';
 
-export interface LatestBuyQuoteOrderDetailsProps {}
-
-interface ConnectedState {
-    buyQuoteInfo?: BuyQuoteInfo;
-    selectedAssetUnitAmount?: BigNumber;
-    ethUsdPrice?: BigNumber;
-    isLoading: boolean;
-}
+type DispatchProperties = 'onBaseCurrencySwitchEth' | 'onBaseCurrencySwitchUsd';
 
+interface ConnectedState extends Omit<OrderDetailsProps, DispatchProperties> {}
 const mapStateToProps = (state: State, _ownProps: LatestBuyQuoteOrderDetailsProps): ConnectedState => ({
     // use the worst case quote info
     buyQuoteInfo: oc(state).latestBuyQuote.worstCaseQuoteInfo(),
     selectedAssetUnitAmount: state.selectedAssetUnitAmount,
     ethUsdPrice: state.ethUsdPrice,
     isLoading: state.quoteRequestState === AsyncProcessState.Pending,
+    assetName: assetUtils.bestNameForAsset(state.selectedAsset),
+    baseCurrency: state.baseCurrency,
 });
 
+interface ConnectedDispatch extends Pick<OrderDetailsProps, DispatchProperties> {}
+const mapDispatchToProps = (dispatch: Dispatch<Action>): ConnectedDispatch => ({
+    onBaseCurrencySwitchEth: () => {
+        dispatch(actions.updateBaseCurrency(BaseCurrency.ETH));
+    },
+    onBaseCurrencySwitchUsd: () => {
+        dispatch(actions.updateBaseCurrency(BaseCurrency.USD));
+    },
+});
+
+export interface LatestBuyQuoteOrderDetailsProps {}
 export const LatestBuyQuoteOrderDetails: React.ComponentClass<LatestBuyQuoteOrderDetailsProps> = connect(
     mapStateToProps,
+    mapDispatchToProps,
 )(OrderDetails);
diff --git a/packages/instant/src/redux/actions.ts b/packages/instant/src/redux/actions.ts
index 77e3dec12..9d7a61fc7 100644
--- a/packages/instant/src/redux/actions.ts
+++ b/packages/instant/src/redux/actions.ts
@@ -2,7 +2,7 @@ import { BuyQuote } from '@0x/asset-buyer';
 import { BigNumber } from '@0x/utils';
 import * as _ from 'lodash';
 
-import { ActionsUnion, AddressAndEthBalanceInWei, Asset, StandardSlidingPanelContent } from '../types';
+import { ActionsUnion, AddressAndEthBalanceInWei, Asset, BaseCurrency, StandardSlidingPanelContent } from '../types';
 
 export interface PlainAction<T extends string> {
     type: T;
@@ -43,6 +43,7 @@ export enum ActionTypes {
     RESET_AMOUNT = 'RESET_AMOUNT',
     OPEN_STANDARD_SLIDING_PANEL = 'OPEN_STANDARD_SLIDING_PANEL',
     CLOSE_STANDARD_SLIDING_PANEL = 'CLOSE_STANDARD_SLIDING_PANEL',
+    UPDATE_BASE_CURRENCY = 'UPDATE_BASE_CURRENCY',
 }
 
 export const actions = {
@@ -72,4 +73,5 @@ export const actions = {
     openStandardSlidingPanel: (content: StandardSlidingPanelContent) =>
         createAction(ActionTypes.OPEN_STANDARD_SLIDING_PANEL, content),
     closeStandardSlidingPanel: () => createAction(ActionTypes.CLOSE_STANDARD_SLIDING_PANEL),
+    updateBaseCurrency: (baseCurrency: BaseCurrency) => createAction(ActionTypes.UPDATE_BASE_CURRENCY, baseCurrency),
 };
diff --git a/packages/instant/src/redux/analytics_middleware.ts b/packages/instant/src/redux/analytics_middleware.ts
index 3f7a51707..a86a16b1a 100644
--- a/packages/instant/src/redux/analytics_middleware.ts
+++ b/packages/instant/src/redux/analytics_middleware.ts
@@ -99,6 +99,9 @@ export const analyticsMiddleware: Middleware = store => next => middlewareAction
                 analytics.trackInstallWalletModalClosed();
             }
             break;
+        case ActionTypes.UPDATE_BASE_CURRENCY:
+            analytics.trackBaseCurrencyChanged(curState.baseCurrency);
+            analytics.addEventProperties({ baseCurrency: curState.baseCurrency });
     }
 
     return nextAction;
diff --git a/packages/instant/src/redux/async_data.ts b/packages/instant/src/redux/async_data.ts
index 932eb93e9..884ab103d 100644
--- a/packages/instant/src/redux/async_data.ts
+++ b/packages/instant/src/redux/async_data.ts
@@ -4,7 +4,7 @@ import * as _ from 'lodash';
 import { Dispatch } from 'redux';
 
 import { BIG_NUMBER_ZERO } from '../constants';
-import { AccountState, ERC20Asset, OrderProcessState, ProviderState, QuoteFetchOrigin } from '../types';
+import { AccountState, BaseCurrency, ERC20Asset, OrderProcessState, ProviderState, QuoteFetchOrigin } from '../types';
 import { analytics } from '../util/analytics';
 import { assetUtils } from '../util/asset';
 import { buyQuoteUpdater } from '../util/buy_quote_updater';
@@ -24,7 +24,9 @@ export const asyncData = {
             const errorMessage = 'Error fetching ETH/USD price';
             errorFlasher.flashNewErrorMessage(dispatch, errorMessage);
             dispatch(actions.updateEthUsdPrice(BIG_NUMBER_ZERO));
+            dispatch(actions.updateBaseCurrency(BaseCurrency.ETH));
             errorReporter.report(e);
+            analytics.trackUsdPriceFailed();
         }
     },
     fetchAvailableAssetDatasAndDispatchToStore: async (state: State, dispatch: Dispatch) => {
diff --git a/packages/instant/src/redux/reducer.ts b/packages/instant/src/redux/reducer.ts
index a9a407b7d..8c13c9c72 100644
--- a/packages/instant/src/redux/reducer.ts
+++ b/packages/instant/src/redux/reducer.ts
@@ -14,6 +14,7 @@ import {
     Asset,
     AssetMetaData,
     AsyncProcessState,
+    BaseCurrency,
     DisplayStatus,
     Network,
     OrderProcessState,
@@ -33,6 +34,7 @@ export interface DefaultState {
     latestErrorDisplayStatus: DisplayStatus;
     quoteRequestState: AsyncProcessState;
     standardSlidingPanelSettings: StandardSlidingPanelSettings;
+    baseCurrency: BaseCurrency;
 }
 
 // State that is required but needs to be derived from the props
@@ -64,6 +66,7 @@ export const DEFAULT_STATE: DefaultState = {
         animationState: 'none',
         content: StandardSlidingPanelContent.None,
     },
+    baseCurrency: BaseCurrency.USD,
 };
 
 export const createReducer = (initialState: State) => {
@@ -243,6 +246,11 @@ export const createReducer = (initialState: State) => {
                         animationState: 'slidOut',
                     },
                 };
+            case ActionTypes.UPDATE_BASE_CURRENCY:
+                return {
+                    ...state,
+                    baseCurrency: action.data,
+                };
             default:
                 return state;
         }
diff --git a/packages/instant/src/types.ts b/packages/instant/src/types.ts
index d217c1a4f..ae672c919 100644
--- a/packages/instant/src/types.ts
+++ b/packages/instant/src/types.ts
@@ -26,6 +26,11 @@ export enum QuoteFetchOrigin {
     Heartbeat = 'Heartbeat',
 }
 
+export enum BaseCurrency {
+    USD = 'USD',
+    ETH = 'ETH',
+}
+
 export interface SimulatedProgress {
     startTimeUnix: number;
     expectedEndTimeUnix: number;
diff --git a/packages/instant/src/util/analytics.ts b/packages/instant/src/util/analytics.ts
index 21d3a4d9e..4faeaaf5a 100644
--- a/packages/instant/src/util/analytics.ts
+++ b/packages/instant/src/util/analytics.ts
@@ -6,6 +6,7 @@ import { GIT_SHA, HEAP_ENABLED, INSTANT_DISCHARGE_TARGET, NODE_ENV, NPM_PACKAGE_
 import {
     AffiliateInfo,
     Asset,
+    BaseCurrency,
     Network,
     OrderProcessState,
     OrderSource,
@@ -37,6 +38,7 @@ enum EventNames {
     ACCOUNT_UNLOCK_REQUESTED = 'Account - Unlock Requested',
     ACCOUNT_UNLOCK_DENIED = 'Account - Unlock Denied',
     ACCOUNT_ADDRESS_CHANGED = 'Account - Address Changed',
+    BASE_CURRENCY_CHANGED = 'Base Currency - Changed',
     PAYMENT_METHOD_DROPDOWN_OPENED = 'Payment Method - Dropdown Opened',
     PAYMENT_METHOD_OPENED_ETHERSCAN = 'Payment Method - Opened Etherscan',
     PAYMENT_METHOD_COPIED_ADDRESS = 'Payment Method - Copied Address',
@@ -48,6 +50,7 @@ enum EventNames {
     BUY_TX_SUBMITTED = 'Buy - Tx Submitted',
     BUY_TX_SUCCEEDED = 'Buy - Tx Succeeded',
     BUY_TX_FAILED = 'Buy - Tx Failed',
+    USD_PRICE_FETCH_FAILED = 'USD Price - Fetch Failed',
     INSTALL_WALLET_CLICKED = 'Install Wallet - Clicked',
     INSTALL_WALLET_MODAL_OPENED = 'Install Wallet - Modal - Opened',
     INSTALL_WALLET_MODAL_CLICKED_EXPLANATION = 'Install Wallet - Modal - Clicked Explanation',
@@ -119,6 +122,7 @@ export interface AnalyticsEventOptions {
     selectedAssetSymbol?: string;
     selectedAssetData?: string;
     selectedAssetDecimals?: number;
+    baseCurrency?: string;
 }
 export enum TokenSelectorClosedVia {
     ClickedX = 'Clicked X',
@@ -142,6 +146,7 @@ export const analytics = {
         window: Window,
         selectedAsset?: Asset,
         affiliateInfo?: AffiliateInfo,
+        baseCurrency?: BaseCurrency,
     ): AnalyticsEventOptions => {
         const affiliateAddress = affiliateInfo ? affiliateInfo.feeRecipient : 'none';
         const affiliateFeePercent = affiliateInfo ? parseFloat(affiliateInfo.feePercentage.toFixed(4)) : 0;
@@ -160,6 +165,7 @@ export const analytics = {
             selectedAssetName: selectedAsset ? selectedAsset.metaData.name : 'none',
             selectedAssetData: selectedAsset ? selectedAsset.assetData : 'none',
             instantEnvironment: INSTANT_DISCHARGE_TARGET || `Local ${NODE_ENV}`,
+            baseCurrency,
         };
         return eventOptions;
     },
@@ -171,6 +177,8 @@ export const analytics = {
     trackAccountUnlockDenied: trackingEventFnWithoutPayload(EventNames.ACCOUNT_UNLOCK_DENIED),
     trackAccountAddressChanged: (address: string) =>
         trackingEventFnWithPayload(EventNames.ACCOUNT_ADDRESS_CHANGED)({ address }),
+    trackBaseCurrencyChanged: (currencyChangedTo: BaseCurrency) =>
+        trackingEventFnWithPayload(EventNames.BASE_CURRENCY_CHANGED)({ currencyChangedTo }),
     trackPaymentMethodDropdownOpened: trackingEventFnWithoutPayload(EventNames.PAYMENT_METHOD_DROPDOWN_OPENED),
     trackPaymentMethodOpenedEtherscan: trackingEventFnWithoutPayload(EventNames.PAYMENT_METHOD_OPENED_ETHERSCAN),
     trackPaymentMethodCopiedAddress: trackingEventFnWithoutPayload(EventNames.PAYMENT_METHOD_COPIED_ADDRESS),
@@ -236,4 +244,5 @@ export const analytics = {
             fetchOrigin,
         });
     },
+    trackUsdPriceFailed: trackingEventFnWithoutPayload(EventNames.USD_PRICE_FETCH_FAILED),
 };
diff --git a/packages/instant/src/util/asset.ts b/packages/instant/src/util/asset.ts
index 13f84ef74..faaeb7c22 100644
--- a/packages/instant/src/util/asset.ts
+++ b/packages/instant/src/util/asset.ts
@@ -2,6 +2,7 @@ import { AssetBuyerError } from '@0x/asset-buyer';
 import { AssetProxyId, ObjectMap } from '@0x/types';
 import * as _ from 'lodash';
 
+import { DEFAULT_UNKOWN_ASSET_NAME } from '../constants';
 import { assetDataNetworkMapping } from '../data/asset_data_network_mapping';
 import { Asset, AssetMetaData, ERC20Asset, Network, ZeroExInstantError } from '../types';
 
@@ -71,7 +72,7 @@ export const assetUtils = {
         }
         return metaData;
     },
-    bestNameForAsset: (asset?: Asset, defaultName: string = '???'): string => {
+    bestNameForAsset: (asset?: Asset, defaultName: string = DEFAULT_UNKOWN_ASSET_NAME): string => {
         if (_.isUndefined(asset)) {
             return defaultName;
         }
diff --git a/packages/instant/src/util/format.ts b/packages/instant/src/util/format.ts
index e9c432b2f..4adb63e21 100644
--- a/packages/instant/src/util/format.ts
+++ b/packages/instant/src/util/format.ts
@@ -2,7 +2,7 @@ import { BigNumber } from '@0x/utils';
 import { Web3Wrapper } from '@0x/web3-wrapper';
 import * as _ from 'lodash';
 
-import { ETH_DECIMALS } from '../constants';
+import { BIG_NUMBER_ZERO, ETH_DECIMALS } from '../constants';
 
 export const format = {
     ethBaseUnitAmount: (
@@ -20,24 +20,38 @@ export const format = {
         ethUnitAmount?: BigNumber,
         decimalPlaces: number = 4,
         defaultText: React.ReactNode = '0 ETH',
+        minUnitAmountToDisplay: BigNumber = new BigNumber('0.00001'),
     ): React.ReactNode => {
         if (_.isUndefined(ethUnitAmount)) {
             return defaultText;
         }
-        const roundedAmount = ethUnitAmount.round(decimalPlaces).toDigits(decimalPlaces);
-        return `${roundedAmount} ETH`;
+        let roundedAmount = ethUnitAmount.round(decimalPlaces).toDigits(decimalPlaces);
+
+        if (roundedAmount.eq(BIG_NUMBER_ZERO) && ethUnitAmount.greaterThan(BIG_NUMBER_ZERO)) {
+            // Sometimes for small ETH amounts (i.e. 0.000045) the amount rounded to 4 decimalPlaces is 0
+            // If that is the case, show to 1 significant digit
+            roundedAmount = new BigNumber(ethUnitAmount.toPrecision(1));
+        }
+
+        const displayAmount =
+            roundedAmount.greaterThan(BIG_NUMBER_ZERO) && roundedAmount.lessThan(minUnitAmountToDisplay)
+                ? `< ${minUnitAmountToDisplay.toString()}`
+                : roundedAmount.toString();
+
+        return `${displayAmount} ETH`;
     },
     ethBaseUnitAmountInUsd: (
         ethBaseUnitAmount?: BigNumber,
         ethUsdPrice?: BigNumber,
         decimalPlaces: number = 2,
         defaultText: React.ReactNode = '$0.00',
+        minUnitAmountToDisplay: BigNumber = new BigNumber('0.00001'),
     ): React.ReactNode => {
         if (_.isUndefined(ethBaseUnitAmount) || _.isUndefined(ethUsdPrice)) {
             return defaultText;
         }
         const ethUnitAmount = Web3Wrapper.toUnitAmount(ethBaseUnitAmount, ETH_DECIMALS);
-        return format.ethUnitAmountInUsd(ethUnitAmount, ethUsdPrice, decimalPlaces);
+        return format.ethUnitAmountInUsd(ethUnitAmount, ethUsdPrice, decimalPlaces, minUnitAmountToDisplay);
     },
     ethUnitAmountInUsd: (
         ethUnitAmount?: BigNumber,
@@ -48,7 +62,13 @@ export const format = {
         if (_.isUndefined(ethUnitAmount) || _.isUndefined(ethUsdPrice)) {
             return defaultText;
         }
-        return `$${ethUnitAmount.mul(ethUsdPrice).toFixed(decimalPlaces)}`;
+        const rawUsdPrice = ethUnitAmount.mul(ethUsdPrice);
+        const roundedUsdPrice = rawUsdPrice.toFixed(decimalPlaces);
+        if (roundedUsdPrice === '0.00' && rawUsdPrice.gt(BIG_NUMBER_ZERO)) {
+            return '<$0.01';
+        } else {
+            return `$${roundedUsdPrice}`;
+        }
     },
     ethAddress: (address: string): string => {
         return `0x${address.slice(2, 7)}…${address.slice(-5)}`;
diff --git a/packages/instant/test/util/format.test.ts b/packages/instant/test/util/format.test.ts
index fe0a63e6e..38bf356ec 100644
--- a/packages/instant/test/util/format.test.ts
+++ b/packages/instant/test/util/format.test.ts
@@ -41,6 +41,18 @@ describe('format', () => {
         it('converts BigNumber(5.3014059295032) to the string `5.301 ETH`', () => {
             expect(format.ethUnitAmount(BIG_NUMBER_IRRATIONAL)).toBe('5.301 ETH');
         });
+        it('shows 1 significant digit when rounded amount would be 0', () => {
+            expect(format.ethUnitAmount(new BigNumber(0.00003))).toBe('0.00003 ETH');
+            expect(format.ethUnitAmount(new BigNumber(0.000034))).toBe('0.00003 ETH');
+            expect(format.ethUnitAmount(new BigNumber(0.000035))).toBe('0.00004 ETH');
+        });
+        it('shows < 0.00001 when hits threshold', () => {
+            expect(format.ethUnitAmount(new BigNumber(0.000011))).toBe('0.00001 ETH');
+            expect(format.ethUnitAmount(new BigNumber(0.00001))).toBe('0.00001 ETH');
+            expect(format.ethUnitAmount(new BigNumber(0.000009))).toBe('< 0.00001 ETH');
+            expect(format.ethUnitAmount(new BigNumber(0.0000000009))).toBe('< 0.00001 ETH');
+            expect(format.ethUnitAmount(new BigNumber(0))).toBe('0 ETH');
+        });
         it('returns defaultText param when ethUnitAmount is not defined', () => {
             const defaultText = 'defaultText';
             expect(format.ethUnitAmount(undefined, 4, defaultText)).toBe(defaultText);
@@ -86,6 +98,12 @@ describe('format', () => {
         it('correctly formats 5.3014059295032 ETH to usd according to some price', () => {
             expect(format.ethUnitAmountInUsd(BIG_NUMBER_IRRATIONAL, BIG_NUMBER_FAKE_ETH_USD_PRICE)).toBe('$13.43');
         });
+        it('correctly formats amount that is less than 1 cent', () => {
+            expect(format.ethUnitAmountInUsd(new BigNumber(0.000001), BIG_NUMBER_FAKE_ETH_USD_PRICE)).toBe('<$0.01');
+        });
+        it('correctly formats exactly 1 cent', () => {
+            expect(format.ethUnitAmountInUsd(new BigNumber(0.0039), BIG_NUMBER_FAKE_ETH_USD_PRICE)).toBe('$0.01');
+        });
         it('returns defaultText param when ethUnitAmountInUsd or ethUsdPrice is not defined', () => {
             const defaultText = 'defaultText';
             expect(format.ethUnitAmountInUsd(undefined, undefined, 2, defaultText)).toBe(defaultText);