Huge action in SPY exchange-traded fund

quoting OptionMonster: "The option action is clearly coming from a large player, as 720,000 contracts changed hands in a single trade. This is one of the largest trades we have seen; for perspective, it represents roughly the entire last month of trading in Yahoo options. It appears that the trader had been long a put backspread, short 120,000 of the December 95 puts and long 240,000 of the December 82 puts, which were sold today at the same time that a new spread was bought in the March 100 and 85 puts. It seems that this investor sold 120,000 of the March 100 puts for $3.21 and bought 240,000 of the March 85 puts for $1.01. This backspread creates a credit that is kept if the SPY is above $100 at expiration. The maximum risk is if the ETF is at that lower $85 strike at expiration. This is very likely a protective position on long shares or some other type of hedge position. The timing of the trade might have something to do with the recent rally in the SPY and the desire to have protection closer to the actual price of the underlying."