SPY options that expire today (highest open interest):
105 put has 62,410 open interest
107 call has 51,523 open interest
ES options that expire today (highest open interest):
1040 put has 3,036 open interest
1070 call has 3,578 open interest
Once you tick it to a new low then you will get shorties who will sell that fractal. Then you can take the market right back up and get them stopped out. You win, the shorties lose (this is for daytraders and other shorter time frame people who do not have the capital for longer term plays...
If you are a customer for one of the floor based executing brokers (i.e.., you call the floor with orders in the big contracts) you can get the information from them.
Saliva, there were actually a bunch of ES options that expired at the end of month.
http://www.cmegroup.com/trading/equity-index/european-style-eom/e-mini-sandp500-eom_contract_specifications.html