** Shares of marketing platform AppLovin APP.O fall 11.6% to $289.72 in afternoon trading

** Muddy Waters Research has taken short position on AppLovin

** Muddy Waters says web traffic analysis leads it to estimate that ~52% of APP's e-commerce conversions are retargeting and incrementality is only ~25%-35%

** APP did not immediately respond to a Reuters request for comment

** Muddy Waters says code evidences that APP is collecting and structuring user IDs from its key platform partners, which appears to be a major violation of the platforms' terms of service

** In February, two short sellers, Fuzzy Panda Research and Culper Research, disclosed short positions in AppLovin and alleged various concerns about co's business practices

** Up to last close, APP down ~1% this year

(Reporting by Jaspreet Singh in Bengaluru)

((Jaspreet.Singh@thomsonreuters.com ; https://twitter.com/i_jass))