Earlier today we announced yet another addition to the amount of shares available in the upcoming Facebook Initial Public Offering (IPO). As you may recall, last Friday traders were already calling around looking for more shares, and on Monday, the available shares were all already spoken for. Then on Tuesday, Facebook and their underwriters added over 50 million more shares and raised the target price range by about $4.

Tomorrow they will finally set the price and trading will begin on Friday. I think we can assume at this point however, that they are done adding shares to the offering. One question that came to my mind is where did these extra shares come from? Speaking specifically about the 25% more from this mourning, they came from early Facebook investors and company insiders.

PayPal’s Peter Thiel was an early investor and he has offered some of his stock. Tiger Global Management will sell 23.4 million of their shares, and Accel Partners will contribute 11 million of their shares to the IPO. In total 84 million more shares have been made available.

The grand total of shares available has grown to 421.2 million and the amount they stand to raise could reach $16 billion depending on what the price ends up being tomorrow. As you may already know, Facebook will be traded on the Nasdaq stock exchange under the ticker symbol “FB”. We’ll keep you updated as the Facebook IPO continues to evolve.