By Noel Randewich

SAN FRANCISCO (Reuters) - Shares of video game maker Activision Blizzard and rival Electronic Arts extended months-long Wall Street rallies in September as investors eyed new versions of high-profile franchises such as "FIFA" and "Call of Duty," analysts said.

Since the end of February, Activision has surged 39 percent, while EA has risen 12 percent since the start of July and both companies have attracted new institutional investors.

In the current quarter, 189 mutual funds and exchange traded funds became new shareholders of Activision, resulting in 116 net new purchasers after divestments by other funds, according to research firm Morningstar. EA attracted 76 net new fund investors.

"They've got the right games, a strong market and the economy is reasonable, so I expect financial upside," Benchmark Company analyst Mike Hickey said of EA. He recommends buying shares of Activision and EA.

Morgan Stanley last week launched coverage of both companies, assigning them "overweight" ratings and pointing to their growing ability to sell digital maps, weapons and other downloadable extras to gamers long after a game's initial purchase.

None of the stock analysts covering Activision and EA recommend selling them.

MKM Partners analyst Eric Handler, one of three analysts with a "hold" rating on Activision, said it would be too hard in 2017 to beat the company's recent successes, including multiplayer game "Overwatch" and an expansion to its "World of Warcraft" series.

"They've had a huge success with 'Overwatch' this year and I think that's going to make for difficult comparisons," Handler said. "I think growth may be more difficult than people expect."

In September, Activision has risen 7 percent and EA is up 3 percent amid a flurry of new releases.

Activision's "Call of Duty: Infinite War" goes on sale in early November and a "Destiny" sequel is planned for next year.

"FIFA 17," the newest version of EA's top-selling soccer franchise, debuted globally on Thursday, and its "Battlefield 1" and "Titanfall 2" first-person shooters are set to launch in late October.

EA's stock has recently traded at 22 times expected earnings, in line with its average over the past five years, according to Thomson Reuters Datastream. Activision trades at 21 times expected earnings, above its average of 16.

Shares of EA were down 0.9 percent on Thursday and Activision edged down 0.1 percent, while the S&P 500 declined 0.9 percent.

(Reporting by Noel Randewich; Editing by Rodrigo Campos and Richard Chang)