[ by Melanie Gretchen ] Morgan Stanley experienced its lowest closing price since December 2008, amid a potential credit-rating cut, Europe’s debt crisis, and lower trading revenue.  The world's largest brokerage fell 37¢, or 2.9%, to $12.36 at 4 p.m. in New York on Monday – the lowest since 12/2/08, less than 3 months after the collapse of Lehman Brothers sent shock waves through global markets. What We're Looking At. Moody’s Investors Service could reduce Morgan Stanley’s credit ratings by as many as 3 levels, more than any U.S. lender.  As a result, the firm would have to post added collateral and pay more to borrow going forward. Morgan Stanley's industry prognosis isn't good. Ed Najarian, an analyst at International Strategy & Investment Group Inc., said in a note Sunday that the firm’s fixed-income trading revenue probably will drop by half in the second quarter as risk-averse clients pull back.  Charles Peabody, an analyst with Portales Partners LLC, blamed "the lack of their core funding structure," in an interview earlier this week on the “Bloomberg Surveillance” radio program: "They don’t have the same core deposit base that a Bank of America or a Citigroup or even a JPMorgan might have.  I think it also has to do with where the franchise is in its evolution.  They’re still very much in a transition phase." Where Morgan Stanley Stands. Currently, the shares of New York-based Morgan Stanley are now trading at 45% of tangible book value, the lowest among the 6 largest U.S. banks and a level that CEO James Gorman described as "inexplicable" last month. Tangible book value calculates the theoretical liquidation value of a firm that excludes assets such as brand names that would be worth little or nothing if a company went out of business.  For more than 2 years, Morgan Stanley has traded below its total book value. Trading Bottom. From the sidelines, Mr. Najarian cut his price target for the shares to $15 from $18 and maintained his "hold" rating.  Mr. Peabody said earlier this week that he had previously said Morgan Stanley may slide further, to as low as $12, rating the stock "sector perform." "We’re there.  Could we go lower than $12?  Maybe temporarily, but generally speaking with the financials, I’m getting closer to thinking we’re reaching some kind of trading bottom." For further details, go to [Bloomberg, 6/4/12].