Quote from YIELDSAFE:
Trade #9 (opened on 5/17/12)
Sold TLT Jun 16 2012 126.0 Call @ 0.89
Bought TLT Jun 16 2012 128.0 Call @ 0.57
Net Credit of 0.32
Trade #9 (closed on 6/14/12)
Bought to close TLT Jun 16 2012 126.0 Call @ 0.33
Sold to close TLT Jun 16 2012 128.0 Call @ 0.03
Net Debit of 0.30
Return = 0.02 (original credit of 0.32 minus debit of 0.30)
Return% = 0.02 / 1.68 = 1.19%