I am new to options and am confused about spreads. Yesterday, I put on a GRPN Bear Put Spread by buying Feb 22 puts and selling Feb 21 puts for a net debit of $0.45 per. My (apparently incorrect) understanding of how a vertical spread worked was that if GRPN traded below 21, the spread should be worth at least $1, as that would be the intrinsic value. However, GRPN is trading at 20.46 at the moment, and even if I could close out the spread at the ask & bid, it would only be worth $0.80 (sell the 22 puts at the ask of 2, buy back the 21 puts at the bid of 1.20). So I obviously I have a flawed understanding of how these spreads work. What mistake am I making here?