Why would you buy options that will end before the full run up? I just don't get it. Good Luck anyway. Gorge made the more "correct" trade. He at least has a chance to recoup if agnc does an offering or something bad happens. Too many things can go bad, but the run up AFTER dec options are mostly certain.
Its a crap shoot. I thought the Sept EX would fall after the Sept OPEX and it didn't. In fact, the dates have been moving up. There has not been a Q in the last 7, that has had the EX after the 21st of that respective EX month. Dec OPEX is late(Dec 21st). Those Dec Calls might be OK. That is what the MM's believe also, as the options (Puts) are priced for the EX occurring on or before the 21st.
Ultimately, you are correct. If you can pick up January for about the same price as Dec on the Calls you are better covered in case the EX occurs after the 21st. We'll see soon...;-)