On both purchase and sale, as of a broker's commission. see also round-turn.

A fee made by a broker involved in both sides (purchase and sale) of a trade.

The commission made by a broker for the purchase and sale sides of a trade.

A broker's commission from his or her involvement on both the purchase and the sale side of a security. Source

Commissions made by a broker who was involved in both the buy and the sell side of a transaction. See: Commission