It was just a few weeks ago that Accel Partners sold off around half a billion dollars of Facebook shares at a company valuation of $35 billion. If you thought that was insane, and a lot of commenters did, then don&'t read the rest of this post. You&'ll only get more jealous.

Around $40 million changed hands last week in a Facebook share auction held by SecondMarket. The end price per share was $20.76, and about 1.9 million shares were bought and sold. And based on there being around 2.5 billion shares outstanding after a 5-1 stock split earlier this year, that values Facebook at around $50 billion. As far as we know, this is an all time high.

At a $50 billion valuation Facebook is has more than 1/4th the market capitalization of Google, and nearly 1/4th the value of Microsoft. It&'s worth more than eBay and Yahoo as well, and closing on Amazon&'s $80 billion valuation.

The email sent out to auction participants is below. A new auction is beginning shortly. We&'ve reached out to SecondMarket for comment.

To All Facebook Market Participants:

Thank you for your feedback and participation in last week‚a4‚¬‚a4„s Facebook auction. As we had hoped, there was robust seller and buyer participation &8212' the auction fully cleared at a per share price of $20.76. In addition, there was overwhelmingly positive feedback on the auction process. As a result, we will be continuing to conduct these auctions for the foreseeable future. For this week, the process will remain reasonably similar, with slight tweaks to the timeline. The reserve price for this week will be $20.60, the same as last week.

If you own shares that you are eligible to sell and wish to participate as a seller, please complete the attached Seller Information Sheet and submit it to SecondMarket at fb@secondmarket.com by tonight, Monday, November 29th, at midnight EST.

If you would like to participate as a buyer, please complete the attached Buyer Information Sheet and submit it to SecondMarket at fb@secondmarket.com by Wednesday, December 1st at 12:00 PM EST.

Please see below for more detailed results on last week‚a4‚¬‚a4„s auction and for this week‚a4‚¬‚a4„s auction calendar:

11/22-11/26 Auction Results:

Total Number of Shares Offered for Sale: 1,896,265 Number of Shares Cleared in Auction: 1,896,265 Reserve Price: $20.60 Clearing Price: $20.76

11/29-12/3 Auction Timeline:

a4s‚· Monday, November 29th at 10:00 AM EST ‚a4‚¬‚a4œ Auction process commences

a4s‚· Monday, November 29th at 11:59 PM EST ‚a4‚¬‚a4œ Seller order forms due

a4s‚· Tuesday, November 30th at 9:00 AM EST ‚a4‚¬‚a4œ Buyers informed of share quantity available

a4s‚· Wednesday, December 1st at 12:00 PM EST ‚a4‚¬‚a4œ Buyer order forms due

a4s‚· Wednesday, December 1st at 5:00 PM EST ‚a4‚¬‚a4œ Participants informed of auction results

a4s‚· Wednesday, December 1st at 8:00 PM EST ‚a4‚¬‚a4œ Transaction documentation distributed to buyers and sellers

a4s‚· Friday, December 3rd at 4:00 PM EST ‚a4‚¬‚a4œ Completed transaction documentation due from buyers and sellers

a4s‚· Friday, December 3rd at 7:00 PM EST ‚a4‚¬‚a4œ Notice to be sent to Facebook, Inc.