A Pennsylvania federal judge on Thursday dismissed a proposed class action alleging market makers in the Philadelphia Stock Exchange conspired to cheat smaller options traders of stock dividends, finding the investor bringing the suit couldn’t show the traders’ conduct was unlawful.

U.S. District Judge Gerald A. McHugh agreed to toss a complicated case alleging that market makers on the Philadelphia exchange, including Sumo Capital LLC, Susquehanna International Group LLP and Bluefin Trading, sought to manipulate the market in order to increase their chances of being able to reap stock dividends, finding lead investor I. Stephen Rabin had failed to show either the traders or exchange owner NASDAQ OMX Group Inc. were intentionally deceiving other investors. Ballard Spahr was among the firms representing the defendants.

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