Financial Troubleshooting Scenarios

Scenario: "Trade": FIX drop reconciliation

Level: Medium

Type: Fix

Access: Email

Description: FIX (Financial Information eXchange) is a common electronic protocol for trading. Messages are tag=value fields separated by SOH (ASCII 0x01; logs here use |). A message starts with 8= (BeginString), 9= (BodyLength), 35= (MsgType) and ends with 10= (CheckSum). See FIX TagValue encoding.

Our order router sends FIX orders to the exchange gateway and gets fills back. Yesterday the session dropped for a few minutes: the gateway kept executing, the router kept sending, but some fills never made it back.

Both sides log raw FIX 4.2 under /home/admin/fix/: router.log (what the router saw) and gateway.log (authoritative). Useful tags:

35  MsgType: D = NewOrderSingle (order), 8 = ExecutionReport (fill),
             5 = Logout, A = Logon, 4 = SequenceReset (session markers)
11  ClOrdID: client order ID on orders
17  ExecID: fill ID, unique per fill (e.g. EX000431)

Test: fills.dat holds exactly the gateway's fill set: every 17=ExecID from gateway.log is present once, with no extras or duplicates.

The "Check My Solution" button runs the script /home/admin/agent/check.sh, which you can read and execute.

Time to Solve: 20 minutes.

Scenario: "Flip": algo symbol flips

Level: Medium

Type: Fix

Access: Email

Description: FIX (Financial Information eXchange) is an electronic protocol for trading. Messages are tag=value fields separated by SOH (ASCII 0x01; logs here use |). A message starts with 8= (BeginString), 9= (BodyLength), 35= (MsgType) and ends with 10= (CheckSum). See FIX encoding.

Our execution algo has a bug: on some fills it stamps the wrong symbol, e.g. an AAPL execution labeled DELL, GOOG labeled INTC.

You get three files: reference market data at /home/admin/market/BANDS.csv (symbol,min_px,max_px bands that never overlap), plus /home/admin/fix/orders.log (35=D orders with 11=ClOrdID and true 55=Symbol) and /home/admin/fix/executions.log (35=8 fills with 17=ExecID, 11=ClOrdID, stamped 55=Symbol, 31=LastPx).

FIX tag dictionary (lines look like 8=FIX.4.2|9=...|...|10=...|, | in place of the SOH delimiter):

35  MsgType: D = NewOrderSingle (order), 8 = ExecutionReport (fill)
11  ClOrdID: client order ID (links a fill back to its order)
17  ExecID: fill ID, unique per fill (e.g. EX000123)
55  Symbol: true symbol on orders, as-stamped (possibly wrong) on fills
31  LastPx: price of this fill

Test: corrections.csv lists exactly the flipped fills (~25 of ~960): every ExecID paired with its true symbol, no missing, extras, or duplicates.

The "Check My Solution" button runs the script /home/admin/agent/check.sh, which you can read and execute.

Time to Solve: 25 minutes.

Scenario: "Pos": position manager down + reconcile

Level: Hard

Type: Fix

Access: Email

Description: FIX (Financial Information eXchange) is a common electronic protocol for trading. Messages are tag=value fields separated by SOH (ASCII 0x01; logs here use |). A message starts with 8= (BeginString), 9= (BodyLength), 35= (MsgType) and ends with 10= (CheckSum). See FIX TagValue encoding.

Dev just called: a deployment of the position manager service (posmgr, a systemd service) went wrong in prod. They've asked you to take a look — posmgr show just errors. Get the service back to active first.

Once it is up, query the service for its CURRENT view (posmgr show). That view is stale: the authoritative trade history is /home/admin/fix/executions.log, raw FIX 4.2 35=8 fills carrying 55=Symbol, 54=Side (1=Buy, 2=Sell) and 32=LastQty.

FIX tag dictionary (lines look like 8=FIX.4.2|9=...|35=8|...|10=...|, | in place of the SOH delimiter):

35  MsgType: D = NewOrderSingle (order), 8 = ExecutionReport (fill)
11  ClOrdID: client order ID (links a fill back to its order)
17  ExecID: fill ID, unique per fill (e.g. EX000151)
55  Symbol: e.g. AAPL, MSFT, TSLA, NVDA, AMD
54  Side: 1 = Buy, 2 = Sell
32  LastQty: shares in this fill
31  LastPx: price of this fill

Test: posmgr.service is active and positions.csv holds exactly the nets from executions.log: every symbol with its true net qty, no missing, extras or dups.

The "Check My Solution" button runs the script /home/admin/agent/check.sh, which you can read and execute.

Time to Solve: 30 minutes.