The lot size of a security or index refers to the number of units that are traded in a single transaction. In the case of the Nifty 50 index and the Bank Nifty index, the lot size is determined by the National Stock Exchange of India (NSE).

The lot size of the Nifty 50 index is currently 50, while the lot size of the Bank Nifty index is currently 25. This means that when trading the Nifty 50 index, the minimum trade size is 50 units, and when trading the Bank Nifty index, the minimum trade size is 25 units.

The lot size for both the Nifty 50 index and the Bank Nifty index is subject to change based on market conditions and other factors. Investors and traders should be aware of the current lot size when trading these indices and should ensure that they are adhering to the minimum trade size requirements.
In the share market, the lot size is an important factor to consider when trading securities or indices, as it determines the minimum trade size and can impact the potential profit or loss on a trade. It is important for investors and traders to be familiar with the lot size of the securities or indices that they are trading in order to make informed decisions about their trades.