[mey]

pre-IPO, means a company that is not publicly traded on the open markets.

securitize (i assume) means to make their stock, or some portion of facebook liquid enough for buy/sell on a market. If there aren't people out there willing to buy or sell facebook that last part won't work.

Shorting something (in financial terms) is to bet against the product. For example, in normal publically traded stocks, you could pay someone to borrow their stocks of a company, sell the stocks off, wait a period of time (duration dependent on deal with original owner), expecting the stocks to loose value, then you rebuy the stocks, hopefully at a lower value. You make the difference between what the stocks started at, and what the ended at, minus the fee for borrowing the stocks.

Shorting stocks is tricky, really only works well over short timelines, and has unlimited downside (unlimited loss potential). For example, if you attempted to short google stock, and then the stock went to some astronomical value, you have to shell out the money to re-buy those google stock to give back to the original owner.