Large customized calendar spread in CBS (CBS, news, chart) options on the PHLX today involving listed and flex-style contracts. With the stock trading near $16.41, an institutional customer bought 50,000 20 strike calls with a custom expiry date of Aug 24th, 2010 against a sale of 50,000 listed Jan-10 20 calls, paying a net debit of 87.5 cents per spread. This appears to roll a large ongoing long out-of-the-money call position which last surfaced in March, when the stock was near $22.85. 52 week low of $15.76 was set Aug 4, and todays flow suggests one large player is willing to commit to a long postion nearly 2 years out.