Confused On Vertical Bear Put Spread

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?

 

With one day left to expiry the market has put a time value of $0.20 on the position

 

1) You're focused on what GRPN would be doing at expiration.
2) The extrinsic value in the options is what you're not properly taking into account.
3) You need the passage of time and/or continued downside price movement to wring out that additional 20 cents per spread.