Here's an edge nobody screenshots because it's unglamorous: a 0DTE scalper holds cash most of the day, deploying capital only briefly per trade. In a positive interest-rate environment, that large idle cash balance can earn short-term interest — a small, riskless return on money you're holding anyway. It won't make you rich, but it's real, and it's free.
Why 0DTE traders are mostly in cash
Unlike a buy-and-hold investor whose capital is always deployed, a scalper is flat between trades — often in the market for minutes at a time and in cash for the rest of the session (and overnight). Combined with the cash-buffer rule, the practical reality is that the majority of the account sits in cash the majority of the time. That cash is a large, persistent balance — exactly the kind of thing that earns interest when rates are positive.
Where the interest comes from
Depending on your broker and account, uninvested cash may earn a yield — through a sweep into an interest-bearing option, a money-market position, or short-term Treasury instruments you park it in between trades. In a higher-rate environment, that's a non-trivial annualized yield on the bulk of your capital, earned with essentially zero market risk while you wait for setups. (Specifics depend entirely on your broker and account type — check yours; this is general information, not tax or investment advice.)
Your capital is flat between trades — but it doesn't have to be lazy. In a positive-rate world, the cash a scalper holds by nature can quietly earn its keep.
Keeping it in perspective
This is a minor, honest edge — a small tailwind on your cash, not a trading strategy, and it disappears if short-term rates go to zero. It doesn't change how you trade, and it should never tempt you to hold cash you'd otherwise deploy for a real setup (or vice versa — don't chase yield over trading discipline). But given that risk management already has you holding a buffer, letting it earn short-term interest is simply not leaving free money on the table.