Casino and bingo hall operator Rank has advised its shareholders against accepting a 150p a share offer for the company, saying it "significantly undervalues Rank and its prospects."Malaysian investment firm Guoco on Friday announced, after the close of trading, that it bought an 11.6% stake in Rank, lifting its stake to 40.8% and triggering a mandatory offer. Guoco said the offer was final and will not be increased.The 150p offer price represents a 0.8% premium to the Rank closing price on Friday. Rank, which operates Mecca bingo halls and Grosvenor casinos, noted today that: "The Guoco Group has reiterated its support for Rank and its executive management team by highlighting that Rank's excellent portfolio of businesses is well positioned for future growth."---RG