Demat is essentially about what you own, it could be shares, debentures, bonds or ETFs. Essentially, they are assets that you can own and the demat account signifies that ownership. If you are only trading in futures, options, and currencies, you don't need a Demat account. Only a trading account is required to deal in these asset classes. But if you wish to invest in the stocks and shares of a company, both demat and trading accounts are a necessity. Remember, your demat account is unaffected by intraday trades and by futures & options trades. Intraday trades and F&O trades are purely contracts. They do not result in ownership and hence the demat account is not involved in any way. It is only the trading account that is involved in cases where the contracts are traded. That includes intraday trades, currency futures, currency options, stock futures, index futures, stock options, and index options. They are executed through the trading account but do not impact the demat account in any way.