IPO Bid lot is the minimum number of shares that one can apply for. Suppose a company issues IPO with lot size of 50 shares. Investors can place IPO bid for atleast 1 lot which is equal to 50 shares. All the IPO bids will be placed in multiple of lots say 1 lot, 2 lot or 100 shares, 3 lot of 150 shares, and so on.