A sweep is a block of option orders placed in rapid succession across multiple strikes or expiries by a single trader or institution. The signal is that whoever is making the trade knows something the rest of the market is still pricing in — and is willing to pay up across the chain to get all of it on at once.
What sets a sweep apart
A normal flow tape shows individual trades at the displayed bid or ask, often two or three contracts wide. A sweep is dozens of contracts in the same direction within milliseconds, hitting every available quote on the book, frequently crossing several strikes. The trade prints in time-and-sales under a "block" or "floor" code because the execution was routed that way on purpose.
Bullish vs bearish reads
A bullish call sweep on far-dated strikes shows conviction that price will move higher — the buyer is willing to pay time premium for early exposure. A bearish put sweep into a quiet tape is a far more urgent signal: someone expects a sudden downside event and wants to hedge or speculate before the market catches on. Mixed sweeps (calls + puts) often encode a volatility trade — the buyer expects a move, not a direction.
Why timing matters
Sweeps lead by minutes to hours. By the time the news hits Bloomberg, the position is already on and the ask is up. Watch the unusual-options feed for cluster sweeps across multiple strikes — those signal real conviction, not retail noise. AlphaTerminal's options flow scanner highlights cluster sweeps with a dedicated badge.
Caveats
Not every sweep is signal. Hedge funds sweep spreads to leg into a multi-leg structure without revealing their full hand. Always check open interest change afterward — a sweep followed by a sharp OI bump on the same strike is firmer evidence than the print alone.