* Brad Smith, David Kenny resign from Yahoo board
* Max Levchin appointed to board, effective immediately
* Changes come 5 months after new CEO takes reins
SAN FRANCISCO, Dec 13 (Reuters) - Yahoo Inc said on Thursday that two of its directors have resigned and that PayPal co-founder Max Levchin has been appointed to its board of directors, the latest change to the struggling Internet company under its new chief executive.
The changes come five months after Marissa Mayer, a former Google Inc executive, took the top job, and they complete a boardroom transformation that began in May when activist investor Dan Loeb settled a bitter proxy fight with Yahoo.
With Levchin, Yahoo gets a board member whose Internet industry bona-fides could help the company improve its image in Silicon Valley, where competition for technology engineers is intense.
He represents the fourth Yahoo director who Loeb, the head of hedge fund ThirdPoint LLC, won the right to appoint when he settled his proxy fight with Yahoo.
Levchin, who was also the first investor of online reviews site Yelp Inc, where he serves as chairman of the board, wrote on his personal blog that "a stronger, fast-growing Yahoo, with its tremendous resources is a massive net-positive for the Silicon Valley ecosystem, the market in general and the U.S. economy."
He also cited sentimental attachment to Yahoo, one of the first Web companies, and respect for Mayer's "ballsy" decision to try to revitalize the company as factoring in to his decision to join the board.
"Max is someone I've admired throughout my career for his phenomenal sense for great products and keen focus on user experiences," Mayer said in a statement.
Yahoo said its board now has 11 directors, down from 12. The changes to the board were effective on Tuesday, a Yahoo spokeswoman told Reuters.
The two directors stepping down from Yahoo's board are Intuit Inc Chief Executive Brad Smith and the Weather Channel's CEO, David Kenny.
An Intuit spokeswoman said that Smith, a board member since 2010, had notified Yahoo that he decided not to stand for re-election because he wanted to focus on his role leading Intuit, a tax and financial services software company.
Kenny did not return calls for comment.
Yahoo, one of the Internet industry's Web pioneers, has undergone a series of changes in recent months as Mayer seeks to reverse years of declining revenue and move the company past a tumultuous period that saw several changes in management and strategy.
Mayer has moved aggressively to recruit high-profile technology industry talent as she strives to revitalize a line-up of Web products criticized for failing to keep up with trends in mobile computing and social media.
Shares of Yahoo were down 7 cents at $19.31 on Thursday afternoon on the Nasdaq.
Yahoo's stock has risen roughly 25 percent since Mayer became CEO in July, reaching the highest level since September 2008 when Yahoo co-founder Jerry Yang was CEO.