If stock ABC is trading at $100 and you decide to sell an ITM vertical call spread 90 days out. you short the 90 strike and you buy the 95 strike. the 95 strike has an intrinsic value of $5 and the 90 strike has an intrinsic value of $10. The vertical spread must at least be $10 - $5= $5. This doesn't account for extrinsic value. The premium would actually be a little higher than $5 due to IV and time value, say $5.10 . This is where my question comes along... If you were to short this ITM spread and it stays in the money, you would gain $0.10 from the extrinsic value because your max loss is $5 but you got a premium of $5.10. if it expires OTM, you would profit the full $5.10. In this case, where is the risk that the seller takes? Is it wrong to assume that the spread must be at least worth $5.00?