You see bids and offers at 0 in the market depth because the exchange initially prices all market orders at 0 during specific trading sessions.
When this happens
Pre-open session (9:00 AM to 9:15 AM): All market orders you place during the pre-open session (both regular and After Market Orders or AMO) start at 0 price. The exchange terms these 'At the Open' or ATO orders. Your orders remain at this price until:
- Order matching occurs during the random closure period (9:07 AM to 9:08 AM)
- The exchange determines the equilibrium price
- The market depth updates immediately after price discovery (around 9:08 AM)
Periodic call auction sessions: You will also see 0 displayed in bids and offers for stocks traded in the periodic call auction category. During auction sessions, the exchange initially prices market orders at 0, similar to the pre-market session.
Example scenario
1. The price for MRF was 0 before the equilibrium price discovery.
2. After 9:08 AM, the market depth was updated to show the equilibrium price.
