Ask ten investors whether to put money in monthly or all at once and you will get ten confident answers. The honest one is that it depends on which risk you care about.

What lump sum optimises for

Markets rise more often than they fall. Money invested earlier is exposed to that drift for longer, so on average a lump sum finishes ahead of the same amount drip-fed over a year.

That average hides the bad case. Invest everything the week before a sharp correction and you spend a long time recovering — not because you picked bad companies, but because of when you happened to press the button.

What an SIP optimises for

A systematic investment plan buys the same rupee amount every month, which means you buy more units when prices are low and fewer when they are high. That is not a clever trick; it is arithmetic.

What it really buys you is behavioural. A monthly debit does not ask you to have an opinion about whether today is a good entry point, and it keeps you invested through the months when the news is bad.

The practical answer

If the money is already sitting in your account and you would not panic in a drawdown, lump sum is statistically the better bet.

If the amount is large relative to your total savings, or you know you will check the app every day, splitting it over six to twelve months costs you a little expected return and buys a lot of sleep. That is usually a good trade.

Most people are not choosing between them anyway — they are investing their salary as it arrives, which is an SIP whether they call it one or not.

Investments in securities are subject to market risk. Read all scheme-related documents carefully before investing.