Huge Volume of SPY Puts Options Bought for October

A few days ago we mentioned the huge number of C (Citibank) 4 puts being bought. Last Friday, a very large unbalance in SPY options was also seen. Take a look at the number of calls and puts traded, and the open interest:

Puts were traded 3 to 1 compared to calls. The current open interest 2 to 1 in favour of the puts.

 This could be a sign that some people or institutions out there are buying a lot of protection for potential drops in the market in October.

The (nearly) complete table of options traded on SPY is shown below:

(please click to enlarge)

Regarding Citibank, interestingly, there are now more calls open than puts, 848k versus 657k. However, 104k calls are in-the-money, and 209k puts are in the money: