[ by Larry Goldfarb ] Facebook shares are not only taking a beating from the media and the public, they also are being pummeled by institutional investors.  On a 10-point scale developed by Data Explorers Ltd, bets against the social-media company amount to 4.3% of shares sold in the company’s IPO - the most expensive level on the firm’s scale. The fact that there are about 18 million Facebook shares out on loan indicates short selling, Data Explorers further notes.  All told, FB's underwriters sold over 420 million shares to the public last week. Impact on Price of Facebook Shares. Through Monday, FB shares were down about 18% from their $38 IPO price.  Unfortunately, this large decline was affected by the decision of the Company, along with lead underwriter Morgan Stanley to price the shares at the top-of-the-range offering price considered  - knowing that it would persuade company backers to sell more of their stock, according to a person familiar with the matter.  PIMCO's leading investment guru, Bill Gross, said in reference to CA-based Facebook last week: "I know a bubble when I see one." This point was reiterated by senior research analyst Will Duff Gordon of Data Explorers, who said in a Bloomberg interview, "There’s definitely plenty of people taking the other side here of the tech IPO and thinking it’s a bubble." Comparison to Other Internet IPOs. The stock loans represent about 1% of Facebook’s 2.14 billion Class A and Class B shares outstanding, according to Data Explorers.  By comparison, such stock loans represented 5.3% for Zynga, and 4.1%  for LinkedIn Corp.  Of course, the numbers will likely change as more shares become available to borrow over the next few days. For further details, go to: [Bloomberg, 5/23/12].