UPDATE 1-Renaissance Technologies bought GameStop, AMC shares, filing says

(Adds number of shares, context)

NEW YORK, May 15 (Reuters) - Hedge fund Renaissance Technologies added a new long position in GameStop and significantly increased its position in AMC Entertainment during the first quarter, putting it in position to benefit from the meme stock mania sweeping through the U.S. equity market this week.

Renaissance added 1,004,958 shares of videogame retailer GameStop during the quarter, which had a value of approximately $12.6 million at the end of March, according to a securities filing released on May 13.

Meme stocks have soared this week after an account linked to Keith Gill, the central figure behind the previous meme stock frenzy in 2021, posted messages on social media platform X. The shares started to lose momentum on Wednesday.

Quarterly disclosures of hedge fund managers' stock holdings in 13-F filings with the U.S. Securities and Exchange Commission are one of the few public ways of tracking what hedge fund managers are selling and buying. The disclosures are made 45 days after the end of each quarter and may not reflect current positions.

GameStop shares are up more than 93% for the week and up more than 300% over the last 10 trading days, potentially making Renaissance Technologies' stake now worth nearly $33.5 million if it kept the position.

Renaissance also increased its position in cinema chain AMC by 78% during the first quarter to give it a total of approximately 8.7 million shares, the securities filing showed.

Shares of other companies, including AMC, headphones maker Koss and food storage container company Tupperware have followed GameStop higher. Like GameStop, many of the stocks are heavily shorted.

James Simon, who founded the quantitative hedge fund Renaissance Technologies, died last week at 86.

(Reporting by Carolina Mandl and David Randall, in New York; Editing by Rod Nickel)