Learn › Volatility & the Greeks · Jun 2026 · 2 min read
Theta Decay Explained
Every day you hold an option, a little value quietly evaporates — even if the stock doesn't move at all. That's theta, and it's why so many consistent traders sell options instead of buying them.
What theta is
Theta measures how much value an option loses for each day that passes, holding everything else equal. An option's price has two parts: intrinsic value (how far in-the-money it is) and time value (the premium you pay for the chance it moves further). Theta eats the time value. At expiry, time value is zero — gone.
The melting ice cube
Think of an out-of-the-money option as an ice cube sitting in the sun. Even if nothing dramatic happens, it shrinks a little every day. The buyer is holding the cube hoping for a heatwave (a big move) before it melts; the seller already sold the cube and is happy to watch it disappear.
Why it speeds up near expiry
Theta isn't constant — it accelerates. A 90-day option bleeds time value slowly; the same option in its final week bleeds fast, because there's less and less time for a move to materialise. That's why weekly options decay so quickly, and why sellers often favour the 30–45 day window: enough premium to be worth it, with decay starting to pick up.
Buyers fight theta, sellers collect it
- Buyers (long calls/puts, directional bets) have negative theta — time is the enemy. You can be right on direction and still lose if you're too early or the move is too small.
- Sellers (cash-secured puts, covered calls, credit spreads) have positive theta — time is your ally. Every quiet day, you keep a little more of the premium.
The trade-off
Collecting theta isn't a free lunch. Sellers earn small, steady gains in exchange for taking on the risk of a large adverse move — the classic "picking up nickels" profile. That's fine, as long as you respect the downside and avoid selling into known catalysts that can cause the big move that wipes out months of theta.
How TickerRisk helps
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