TAS (Trade at Settlement) is an order type that executes trades at the official settlement price determined by the exchange, rather than at prevailing market prices during the trading session. TAS orders provide price certainty and eliminate timing risk for traders who want exposure at settlement prices without market timing concerns.

TAS orders are particularly useful for index funds, large institutional trades, or hedging activities where settlement price execution is preferred over intraday pricing. These orders help reduce market impact and provide efficient execution for price-insensitive trades that require settlement price references.

Real-world example: An index fund uses TAS orders to buy crude oil futures at the daily settlement price of $75.50 per barrel, ensuring portfolio tracking accuracy without concern for intraday price movements or execution timing.