diff --git a/src/lib/alarms/csfloat_trade_pings.ts b/src/lib/alarms/csfloat_trade_pings.ts
index 3243032a..872fba1b 100644
--- a/src/lib/alarms/csfloat_trade_pings.ts
+++ b/src/lib/alarms/csfloat_trade_pings.ts
@@ -8,6 +8,7 @@ import {gStore} from '../storage/store';
 import {StorageKey} from '../storage/keys';
 import {reportBlockedBuyers} from './blocked_users';
 import {TradeHistoryStatus} from '../bridge/handlers/trade_history_status';
+import {pingFailedTrades} from './failed_trade';
 import {pingRollbackTrades} from './rollback';
 import {FetchSlimTrades} from '../bridge/handlers/fetch_slim_trades';
 
@@ -73,6 +74,7 @@ interface UpdateErrors {
     trade_offer_error?: string;
     blocked_buyers_error?: string;
     rollback_trades_error?: string;
+    failed_trades_error?: string;
 }
 
 async function pingUpdates(pendingTrades: SlimTrade[], steamID?: string | null): Promise<UpdateErrors> {
@@ -119,5 +121,12 @@ async function pingUpdates(pendingTrades: SlimTrade[], steamID?: string | null):
         errors.rollback_trades_error = (e as any).toString();
     }
 
+    try {
+        await pingFailedTrades(pendingTrades, tradeHistory);
+    } catch (e) {
+        console.error('failed to report failed trades', e);
+        errors.failed_trades_error = (e as any).toString();
+    }
+
     return errors;
 }
diff --git a/src/lib/alarms/failed_trade.test.ts b/src/lib/alarms/failed_trade.test.ts
new file mode 100644
index 00000000..71ea0eef
--- /dev/null
+++ b/src/lib/alarms/failed_trade.test.ts
@@ -0,0 +1,60 @@
+import {describe, expect, it} from 'vitest';
+import {TradeHistoryStatus} from '../bridge/handlers/trade_history_status';
+import {SlimTrade, TradeState} from '../types/float_market';
+import {TradeOfferState, TradeStatus} from '../types/steam_constants';
+import {findFailedTrades} from './failed_trade';
+
+const steamAssetID = '3899876543210123456';
+const otherPartyID = '76561198000000000';
+
+describe('failed Steam trades', () => {
+    it('matches failed history to a relevant pending trade', () => {
+        const matches = findFailedTrades([pendingTrade()], [tradeHistory()]);
+
+        expect(matches).toHaveLength(1);
+        expect(matches[0].csfloatTrade.id).toBe('csfloat-trade-id');
+        expect(matches[0].steamTrade.status).toBe(TradeStatus.Failed);
+    });
+
+    it('does not match an already recorded failed Steam trade', () => {
+        const trade = pendingTrade();
+        trade.steam_trade_failed_id = 'steam-trade-id';
+
+        expect(findFailedTrades([trade], [tradeHistory()])).toEqual([]);
+    });
+
+    it('does not match a trade whose CSFloat offer is accepted', () => {
+        const trade = pendingTrade();
+        trade.steam_offer.state = TradeOfferState.Accepted;
+
+        expect(findFailedTrades([trade], [tradeHistory()])).toEqual([]);
+    });
+});
+
+function pendingTrade(): SlimTrade {
+    return {
+        id: 'csfloat-trade-id',
+        state: TradeState.PENDING,
+        seller_id: otherPartyID,
+        buyer_id: '76561198111111111',
+        contract: {
+            item: {
+                asset_id: steamAssetID,
+                market_hash_name: 'AK-47 | Redline',
+            },
+        },
+        steam_offer: {state: TradeOfferState.Active},
+    } as SlimTrade;
+}
+
+function tradeHistory(): TradeHistoryStatus {
+    return {
+        trade_id: 'steam-trade-id',
+        status: TradeStatus.Failed,
+        other_party_url: `https://steamcommunity.com/profiles/${otherPartyID}`,
+        other_party_id: otherPartyID,
+        received_assets: [{asset_id: steamAssetID}],
+        given_assets: [],
+        time_init: 123,
+    };
+}
diff --git a/src/lib/alarms/failed_trade.ts b/src/lib/alarms/failed_trade.ts
new file mode 100644
index 00000000..9e8c5364
--- /dev/null
+++ b/src/lib/alarms/failed_trade.ts
@@ -0,0 +1,71 @@
+import {TradeHistoryStatus} from '../bridge/handlers/trade_history_status';
+import {StorageKey} from '../storage/keys';
+import {gStore} from '../storage/store';
+import {SlimTrade, TradeState} from '../types/float_market';
+import {TradeOfferState, TradeStatus} from '../types/steam_constants';
+import {reportTradeError} from './error_report';
+import {isBackgroundNotaryRollbackEnabled, proveTradesInBackground} from './notary';
+
+interface FailedTradeInfo {
+    steamTrade: TradeHistoryStatus;
+    csfloatTrade: SlimTrade;
+}
+
+export function findFailedTrades(pendingTrades: SlimTrade[], tradeHistory: TradeHistoryStatus[]): FailedTradeInfo[] {
+    const results: FailedTradeInfo[] = [];
+
+    for (const trade of tradeHistory) {
+        if (trade.status !== TradeStatus.Failed) {
+            continue;
+        }
+
+        const receivedIDs = trade.received_assets.map((asset) => asset.asset_id);
+        const givenIDs = trade.given_assets.map((asset) => asset.asset_id);
+        const assetIDs = [...receivedIDs, ...givenIDs];
+
+        const csfloatTrade = pendingTrades.find(
+            (pendingTrade) =>
+                pendingTrade.state === TradeState.PENDING &&
+                pendingTrade.steam_offer?.state === TradeOfferState.Active &&
+                pendingTrade.steam_trade_failed_id !== trade.trade_id &&
+                assetIDs.includes(pendingTrade.contract.item.asset_id) &&
+                (trade.other_party_id === pendingTrade.seller_id || trade.other_party_id === pendingTrade.buyer_id)
+        );
+        if (!csfloatTrade) {
+            continue;
+        }
+
+        results.push({steamTrade: trade, csfloatTrade});
+    }
+
+    return results;
+}
+
+export async function pingFailedTrades(pendingTrades: SlimTrade[], tradeHistory: TradeHistoryStatus[]) {
+    if (!pendingTrades?.length || !tradeHistory?.length) {
+        return;
+    }
+
+    const failedTrades = findFailedTrades(pendingTrades, tradeHistory);
+    if (failedTrades.length === 0 || !(await isBackgroundNotaryRollbackEnabled())) {
+        return;
+    }
+
+    const lastFailure = await gStore.getWithStorage<number>(
+        chrome.storage.local,
+        StorageKey.LAST_NOTARY_BG_PROOF_FAILURE
+    );
+    if (lastFailure && lastFailure > Date.now() - 60 * 60 * 1000) {
+        console.log('skipping failed-trade notary proof, last failure was less than 60 minutes ago');
+        return;
+    }
+
+    try {
+        await proveTradesInBackground(failedTrades.map((failedTrade) => failedTrade.steamTrade));
+        console.log(`proved ${failedTrades.length} failed trade(s) via notary`);
+    } catch (e) {
+        console.error('failed-trade notary proving failed', e);
+        await gStore.setWithStorage(chrome.storage.local, StorageKey.LAST_NOTARY_BG_PROOF_FAILURE, Date.now());
+        reportTradeError(failedTrades[0].csfloatTrade.id, `background extension failed-trade notary failed: ${e}`);
+    }
+}
diff --git a/src/lib/alarms/notary.ts b/src/lib/alarms/notary.ts
index c0e7c4d5..abbd1bb9 100644
--- a/src/lib/alarms/notary.ts
+++ b/src/lib/alarms/notary.ts
@@ -21,13 +21,14 @@ export async function isBackgroundNotaryRollbackEnabled(): Promise<boolean> {
     }
 }
 
-function buildProveRequest(trades: TradeHistoryStatus[]): NotaryProveRequest {
+export function buildProveRequest(trades: TradeHistoryStatus[]): NotaryProveRequest {
     if (trades.length === 1) {
         return {
             type: ProofType.TRADE_HISTORY,
             max_trades: 5,
             start_after_time: trades[0].time_init,
             navigating_back: true,
+            include_failed: true,
         };
     }
 
@@ -39,6 +40,7 @@ function buildProveRequest(trades: TradeHistoryStatus[]): NotaryProveRequest {
         max_trades: MAX_TRADE_HISTORY_FETCH,
         start_after_time: oldestTimeInit,
         navigating_back: true,
+        include_failed: true,
     };
 }
 
diff --git a/src/lib/alarms/trade_history.ts b/src/lib/alarms/trade_history.ts
index 3ddfd672..8c136060 100644
--- a/src/lib/alarms/trade_history.ts
+++ b/src/lib/alarms/trade_history.ts
@@ -50,7 +50,7 @@ export async function pingTradeHistory(
 
 async function getTradeHistory(): Promise<{history: TradeHistoryStatus[]; type: TradeHistoryType}> {
     try {
-        const history = await getTradeHistoryFromAPI(MAX_TRADE_HISTORY_FETCH);
+        const history = await getTradeHistoryFromAPI(MAX_TRADE_HISTORY_FETCH, {includeFailed: true});
         if (history.length > 0) {
             // Hedge in case this endpoint gets killed, only return if there are results, fallback to HTML parser
             return {history, type: TradeHistoryType.API};
@@ -146,8 +146,9 @@ export async function getTradeHistoryFromAPI(
             (e) =>
                 e.status === TradeStatus.Committed ||
                 e.status === TradeStatus.Complete ||
+                e.status === TradeStatus.Failed ||
                 e.status === TradeStatus.TradeProtectionRollback
-        ) // Only report exchanged/completed trades or trade-protection rollbacks
+        ) // Only report exchanged/completed trades or failed/rolled-back trades
         .filter((e) => !e.time_escrow_end || new Date(parseInt(e.time_escrow_end) * 1000).getTime() < Date.now())
         .map((e) => {
             return {
diff --git a/src/lib/types/float_market.ts b/src/lib/types/float_market.ts
index 2d098fb1..334eb19e 100644
--- a/src/lib/types/float_market.ts
+++ b/src/lib/types/float_market.ts
@@ -104,6 +104,7 @@ export interface Trade {
     state: TradeState;
     trade_url: string;
     steam_offer: SteamOffer;
+    steam_trade_failed_id?: string;
     wait_for_cancel_ping?: boolean;
     seller_blocked_buyer_at?: string;
     buyer_blocked_seller_at?: string;