ORIGINAL COMPANY-CONTEXT PRACTICE
Reconstruct positions at an as-of boundary
Original practice scenario inspired by The Charles Schwab Corporation's public business context; this is not a reported interview question or a description of its internal systems. A fictional brokerage analytics view stores trades, cancellations, and position adjustments. Explain an as-of position query that separates trade date, settlement date, and ingestion time, without presenting the result as investment advice.
Written for independent practice using company context; this is not a verified question from a company interview.
A REASONED APPROACH
Model answer.
State which position definition is required before summing quantities. Trade-date and settled positions answer different operational questions, while ingestion time determines what information was known at the report cutoff.
Work through it
- Normalize signed quantities and stable trade identities. Represent cancellations or corrections through explicit linked events rather than deleting history invisibly.
- Filter by the selected business-date rule and knowledge cutoff, then aggregate by account and instrument. Keep unresolved or late-arriving corrections visible in reconciliation.
- Test a trade settling after the cutoff, a later cancellation, duplicate delivery, and an adjustment without a trade. Compare the result with a small hand-reconciled ledger.
Tradeoffs to discuss
- Historical as-known snapshots and restated positions can both be useful, but must be labeled separately. Corporate actions may require additional domain-specific transformations.
Common pitfalls
- Using settlement date for one table and trade date for another creates inconsistent totals.
- A latest-row query alone does not reconstruct all signed position changes.