UPDATE 3-Kerkorian buys MGM Mirage shares, stake now 42 pct

* Kerkorian investment vehicle buys more MGM shares

* Tracinda stake falls to 42 percent

* JPMorgan upgrades stock

* Shares up 9 pct (Adds analyst comment, updates shares, previously NEW YORK)

LOS ANGELES, May 18 (Reuters) - Billionaire Kirk Kerkorian, the largest shareholder of MGM Mirage (MGM.N: Quote, Profile, Research), has acquired more shares of the casino operator, but his overall stake in the company has fallen, according to a securities filing on Monday.

Shares of the Las Vegas-based company rose about 9 percent to $8.36 on the New York Stock Exchange.

The purchase came on the heels of a $1 billion equity offering by MGM, which lowered the stake held by Kerkorian's Tracinda Corp to about 39 percent, according to Sanford Bernstein analyst Janet Brashear.

The new shares bring Tracinda's holdings to about 42 percent, which is still well below the 53.8 percent held by the Kerkorian-led investment company as of May 13.

The news came as JPMorgan upgraded the stock to "overweight" from "neutral." The brokerage said the improved liquidity position of the company following its stock and bond offerings should alleviate any bankruptcy-risk concerns for at least two years. [ID:nBNG491096]