[ by Melanie Gretchen ] A Bernie Madoff feeder fund dropped a $900 million lawsuit for reasons unknown.  The lawsuit was originally filed in December in NYS Supreme Court by the liquidators of M-Invest, a Cayman Islands corporation, against the fund's auditors, New York-based accounting firm Ernst & Young.  E&Y had audited M-Invest's annual financial statements from 2003. The accountants were accused of negligence, malpractice, and breach of contract;  Ernst & Young said the suit was without merit. The March 23 discontinuation of the action by plaintiffs follows the payment of $500 million by Union Bancaire Privee to Madoff trustee Irving Picard, that settled accusations by Picard  who accused the bank of profiting from Madoff's scheme.  The settlement was concluded, though neither the bank nor M-Invest admitted any liability.  Union Bancaire is a private Swiss bank that set up M-Invest as a conduit for investing money with Madoff. Going forward, the SIPC said that investors in so-called feeder funds aren't customers of Madoff's firm and thus can't make claims on the estate of the bankrupt brokerage. For further details, go to [Crain's New York, 3/26/12].