Seven banks that helped MF Global sells bonds are being sued by pension funds who say the bonds' offering prospectuses concealed problems that ultimately led to the brokerage's collapse. The lawsuit was filed by the IBEW Local 90 Pension Fund in Connecticut, and the Plumbers' and Pipefitters' Local #562 Pension Fund in Missouri, and seeks class-action status against units of Bank of America, Citigroup,  Deutsche Bank, Goldman Sachs,  Jefferies Group,  JPMorgan Chase,  and Royal Bank of Scotland.  Jon Corzine, MF Global's,  Chief Executive and other execs of the bankrupt company were also named as defendants. According to the complaint, the registration statements and prospectuses for about $900 million of MF Global note offerings this year omitted how the company was using high leverage, investing heavily in risky European sovereign debt, and not properly segregating client assets from its own. It said the seven banks helped draft the offering documents and sell the notes, collecting $21.2 million of fees, but that their "failure to conduct an adequate due diligence investigation was a substantial factor" in MF Global's collapse, as well as in defaults on the notes. Friday's lawsuit may be one of the earliest efforts for investors to recover money from relatively deep-pocketed defendants that they believe may share in responsibility for the brokerage's Oct. 31 bankruptcy. It seeks damages for investors between Feb. 3, 2011 and Oct. 31, 2011 in MF Global securities, including its 1.875 percent convertible senior notes maturing in 2016, its 3.375 percent convertible senior notes maturing in 2018, and its 6.25 percent senior notes maturing in 2016. Spokespersons for the banks declined to comment. MF Global is not a defendant because of the bankruptcy.  [Reuters 11/21/11]