By Lawrence Delevingne and Svea Herbst-Bayliss

LAS VEGAS (Reuters) - Hedge fund managers on Thursday named some of their recent investments, including a bet that shares of American Airlines Group (AAL.O) would fall and shares of both Chinese Internet company Tencent and chipmaker Xilinx (XLNX.O) would rise, in addresses at one of the industry's most prominent conferences.

John Lykouretzos, who runs $2.8 billion Hoplite Capital Management Lp, disclosed his negative case against American Airlines, which helped push the stock down as much as 4.7 percent on Thursday.

Calling the company the "most compelling short in the U.S. airline industry," Lykouretzos said American's costs are too high, that it is the most exposed airline to rising oil prices, and it has the highest leverage compared to its peers.

An American airlines spokesman, Josh Freed, responding to Lykouretzos, referred Reuters to recent comments from Chief Executive Doug Parker on a company earnings call.

Parker on that call said American was “purchasing our shares because we are bullish on the stock," and said “the industry is well undervalued," adding, "We think American Airlines has more upside than anyone else in the industry.”

Lykouretzos was one of a handful of prominent managers speaking at the annual SkyBridge Alternatives Conference in Las Vegas, four months into a difficult year where the average hedge fund has lost money and some big-name investors are rethinking their commitment to them.

The managers did not provide details on when they invested in particular companies or at what price.

Fears about a possible recession in the United States and slower growth in China have contributed to unpredictable markets that have left many managers nursing losses.

But there are still good opportunities, the managers told the conference where about 2,000 investors, managers and others crowded in to hear who is picking what.

John Burbank, who runs $4.1 billion Passport Capital and has often invested abroad, said he is betting on Tencent, calling it the "dominant Internet play" with six of the most popular smart-phone apps.

Clifton Robbins of $3.5 billion Blue Harbour Group said he likes Xilinx and was buying more as recently as Thursday. He noted that the company has some $2 billion in cash and said the stock is undervalued, which would make a case for the company buying back some of its own stock.

Activist investors like Blue Harbour have called on many chief executives to buy back their own stock. Robbins also said Xilinx is the last independent chip company after Intel Corp (INTC.O) and Altera merged. Xilinx's unique standing could prompt takeover bids, he said.

Jim Chanos, who runs Kynikos Associates and built his reputation on a successful bet against Enron, spoke again about his short play on Cheniere Energy Inc (LNG.A), saying the stock is still "crazy expensive."

Burbank said he's betting against large Chinese companies via the iShares China Large-Cap ETF to hedge out some of what he called "old China risk."

Meanwhile, Scott Ferguson, who runs $4 billion Sachem Head Capital Management, said his activist firm exited its bet on animal healthcare company Zoetis Inc (ZTS.N) in the first quarter.

Sachem brought the idea on Zoetis to the attention of Pershing Square's William Ackman and both made an investment in 2014. Ferguson said his fund had made money on the bet and Zoetis was very responsive to the activists' suggestions, but it was time to move on and find other opportunities.

Pershing Square recently reduced its holding in Zoetis.

Teresa Barger, chief executive officer of Cartica Management, repeated that her firm is invested in Taiwanese company Voltronic Power .

Jeff Smith of Starboard Value spoke again about his firm's most prominent investment, Yahoo Inc (YHOO.O). Starboard recently reached an agreement with Yahoo under which Starboard will get board seats. Smith said his job as a new board member is to improve the strength of Yahoo's core business.

(Reporting by Lawrence Delevingne and Svea Herbst; Editing by Chris Reese, Tom Brown and Leslie Adler)