"In business, economics or investment, market liquidity is an asset's ability to be sold without causing a significant movement in the price and with minimum l

"In business, economics or investment, market liquidity is an asset's ability to be sold without causing a significant movement in the price and with minimum loss of value. ... Another elegant definition of liquidity is the probability that the next trade is executed at a price equal to the last one. A market may be considered deeply liquid if there are ready and willing buyers and sellers in large quantities. ... The liquidity of a product can be measured as how often it is bought and sold; this is known as volume." I don't think any sane investor would consider private shares of Facebook "plenty" liquid. The volume of Facebook trading is so low that when a large trade of it does occur, as in this additional investment that valued it at $33b, the price jumps wildly and it makes news. As per the secondary market, Sharespost shows the last contract traded on their system being over 3 weeks ago, and that there are only 3 people willing to sell and 5 people willing to buy right now. Those are pathetic numbers. Granted, shares are not entirely illiquid either. You could sell your shares... but it's a necessity that the more you want to sell, the lower your price is going to have to be to attract enough buyers.