By Saqib Iqbal Ahmed

NEW YORK, Oct 7 (Reuters) - Alcoa Inc's shares are expected to move nearly twice as much as they have following other recent earnings reports when the aluminum producer reports third quarter financial results on Wednesday.

Shares of Alcoa, which have risen about 51 percent for the year-to-date, were up about 1 percent at $16.12 on Tuesday.

The cost of a near-term Alcoa straddle, a strategy in which an investor buys an at-the-money put option and a similar call option, suggests a move of about 4.9 percent in either direction by Oct. 10. Over the last eight quarters, Alcoa shares have on average moved 2.8 percent the day after earnings.

Trading in Alcoa's shares has been more volatile lately as it hit a new 52-week high. The stock has dropped more than 7 percent since Sept. 5 as investors worry about global growth trends and the dollar's strength, which has hurt the shares of materials companies, including Alcoa.

"The option market is pricing in elevated risk for this earnings cycle relative to many of the prior cycles in the last two-years," said Ophir Gottlieb, chief executive officer at Los Angeles-based Capital Market Laboratories LLC.

Activity in Alcoa's options was brisk, with Alcoa being the 14th most traded name by volume on Tuesday. More than 25,000 calls had traded by shortly after midday, outnumbering puts by a ratio of 4.5:1, according to Trade Alert data.

Alcoa is expected to report earnings of 23 cents a share, according to Starmine, a Thomson Reuters company, though Starmine's models weighting the highest-rated analysts suggest it could exceed that estimate and earn 24 cents a share.

Implied volatility, a measure of the risk that big moves in a stock pose, has been on the rise for Alcoa shares in the run-up to its third quarter results.

One-month implied volatility for Alcoa has increased 67 percent since the start of September and was at 39.39 percent on Tuesday, ranking in the 88th percentile of its 52-week range, according to Livevol Inc data.

Investors will be eager to get more details on Alcoa's Firth Rixson acquisition, its supply deal with planemaker Boeing Co and the company's outlook for global aluminum trends when the company reports results, analysts said.

(Reporting by Saqib Iqbal Ahmed; Editing by Tom Brown)