Sweep vs block
- Sweep: many fills across exchanges in a split second, usually aggressive.
- Block: one large negotiated trade, often between institutions, at a single price.
- Split: a large order filled in pieces over time on one venue.
What makes a sweep worth a look
- Paid at or above the ask (buyer-initiated).
- Volume larger than existing open interest (a new position).
- Short-dated, out-of-the-money strikes ahead of a catalyst.
- Repeated sweeps in the same direction across the day.