By Dan Levine

Feb 14 (Reuters) - Hedge fund manager David Einhorn's Greenlight Capital has asked a court to order the website Seeking Alpha to disclose the identity of a commenter who disclosed Greenlight's stake in Micron before it was officially announced, according to a court filing.

In an action brought on Thursday in a New York state court, Greenlight said a frequent Seeking Alpha commenter, writing under the pseudonym "Valuable Insights", revealed Einhorn's position last November, which drove up chipmaker Micron's share price.

"Because this was the very time frame in which Greenlight was in the process of building its Micron position, it was forced to pay higher prices for its Micron securities," the court filing said.

A spokesman for Greenlight Capital declined to comment on Friday, and a representative for Seeking Alpha could not immediately be reached.

Greenlight returned 19.5 percent last year. According to the court filing, Greenlight sent a confidentiality letter disclosing the Micron position to the SEC shortly after the Seeking Alpha comments.

"Prior to the Internet postings, the only persons to whom Greenlight disclosed its position in Micron were persons subject to a contractual, fiduciary, or other duty to maintain the confidentiality of that information: Greenlight's employees, legal counsel, prime and executing brokers, fund administrator, and other agents," the filing said.

Greenlight eventually reported a stake of about 23.02 million shares in Micron later in November.

The case in the Supreme Court of the State of New York, County of New York, is In the Matter of the Application of Greenlight Capital Inc., 151327/2014.