Universa Investment LP's Trade

According to WSJ

"Shortly after 2:15 p.m. Eastern time on Thursday, hedge fund Universa Investments LP placed a big bet in the Chicago options trading pits...

On any other day, this $7.5 million trade for 50,000 options contracts...

The trade by Universa, a hedge fund advised by Nassim Taleb, author of "Black Swan: The Impact of the Highly Improbable," led traders on the other side of the transaction—including Barclays Capital, the brokerage arm of British bank Barclays PLC—to do their own selling to offset some of the risk, according to traders in Chicago.

Through the trading desks at Barclays, Universa bought 50,000 options contracts... The contracts would pay off about $4 billion should the Standard & Poor's 500-stock index fall to 800 in June. It was at 1145 points at the time of the trade.
"

According to other news source, Universa  Investment LP has about 6 billions under management in Jun 2009.  The bet is about 0.125% of the fund for a 7 week term.

4 billions profit on 50,000 contracts means 80,000 profit per contract, and 800 per unit.  How to make 800 profit with a drop of only 345 points on SPX?

The original put premium is about 1.25.  If SPX drops to 800 on the same day and the VIX jumps up to 80, the SPX100619P800 premium will be about 93.  The profit is only 92 and the total will be about 460 millions, a 7.67% return.