Why are bids and offers at 0 being displayed in the market depth?

All market orders (Regular and AMO orders) placed during the pre-open session (9:00 AM to 9:15 AM) are initially priced at 0 at the exchange and are termed 'At the Open' or ATO orders. They remain at this price until the order matching happens, and the equilibrium price is determined during the random closure period between 9:07 AM and 9:08 AM. Following this, the market depth gets updated immediately after the equilibrium price is discovered (around 9:08 AM).

This is also applicable for stocks traded in the periodic call auction category. During the auction sessions, 0 might be displayed in the bids and offers in the market depth, as the market orders are initially priced at 0 during these sessions, similar to pre-market session. To learn more, see What is periodic call auction and why are some stocks traded in this category?

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.