CHICAGO (Bloomberg) — Shares of Bermuda company Nabors Industries Ltd., the world’s largest onshore oil and natural-gas driller, had the largest gain in almost four months on speculation the company may be a buyout target, energy analyst Dan Pickering said.The shares jumped $1.35, or 4.5 percent, to $31.55 in New York Stock Exchange composite trading, the biggest one-day percentage increase since October 10. More than 21 million shares changed hands, more than triple the stock’s average daily volume of 6.3 million shares.

Nabors spokesman Dennis Smith declined to comment on the rumours. The company was the subject of similar rumours last year, after chief executive officer Gene Isenberg raised the prospect of a leveraged buyout during an October conference call. Nabors is based in Hamilton and run from offices in Houston.

Pickering, president of Houston-based Pickering Energy Partners, Inc., said any leveraged buyout of Nabors is “possible, but not likely”. Swings in oil and gas prices may hurt profit for drillers such as Nabors, making them risky investments for private equity groups, Pickering said.

“This continues to be more of a Wall Street rumour than a real likelihood,” Pickering said in a phone interview. “We know that there are a lot private equity dollars out there, but there’s still a lot of risk around doing something levered” in the drilling industry.