A risk reversal is a two-leg trade: to get bullish, you sell a put and use the premium to buy a call (bearish flips it — sell a call, buy a put). The short leg finances the long leg, so you can put the position on for little or no net cost.

What you're actually holding

A bullish risk reversal behaves like a synthetic long in the stock: you profit as SPY rises (via the call) and lose as it falls (via the short put), with a premium-neutral entry. It's leveraged directional exposure — but that cheap entry hides the real risk.

The catch: the short leg

That short put is uncovered unless you secure it with cash. If SPY drops, the short put can lose far more than the call cost you, and it carries assignment risk. This is a defined-direction, undefined-loss structure — the opposite of a long single option, whose loss is capped at the premium. It also usually requires a high options approval level.

A risk reversal is cheap to put on and expensive to be wrong in — the free entry is financed by open-ended downside.

The skew connection

There's a reason you'll hear “25-delta risk reversal” in market-structure talk: the price difference between a 25-delta put and a 25-delta call is the standard volatility skew reading. Because indices fall faster than they rise, the put usually costs more — a positive skew, i.e. fear priced into downside. So the risk reversal isn't just a trade; it's the market's fear gauge. As a scalping vehicle, though, its undefined loss makes it a poor fit next to a simple long option.