March 3 (Reuters) - The following are the top stories in the Wall Street Journal. Reuters has not verified these stories and does not vouch for their accuracy.
* The U.S. and its European allies vowed Sunday to isolate Russian President Vladimir Putin and punish his nation's economy, demanding he withdraw what they called an occupation force from Ukraine's Crimean region. ()
* Bruce Berkowitz, a prominent mutual-fund investor, sent letters to the boards of Fannie Mae and Freddie Mac late Friday scolding directors for not protecting the rights of shareholders, upping the ante in his bid to let investors share in the spoils of the newly profitable mortgage-finance giants. ()
* Investors rushed into safe-haven assets and cut their exposure to stocks as an escalating crisis in Ukraine sent a chill through global markets. ()
* Comcast Corp is near a deal to acquire FreeWheel Media Inc, a Web-video company for about $320 million, a person familiar with the matter said. ()
* Pfizer Inc hopes to overcome skepticism that consumers can appropriately take an over-the-counter version of cholesterol pill Lipitor without doctor guidance. ()
* The recent loss of nearly a half-billion dollars from a major bitcoin exchange is forcing U.S. regulators to confront burgeoning questions about their authority-and responsibility-to oversee the fledgling virtual currency. ()
* Warren Buffett and his business partner Charles Munger have long been bullish on the United States, building a "rock-solid foundation" for Berkshire Hathaway Inc with calculated bets on the country's economic future. In 2013, those efforts paid off handsomely for Berkshire shareholders as the gigantic conglomerate posted record annual profits, aided by a generous tailwind from the improving U.S. economy. ()
* Mexican police questioned a Citigroup Inc employee suspected of participating in the alleged theft of $400 million from the bank, according to a person familiar with the matter.
* U.S. aviation regulators want cockpit-automation fixes on nearly 500 Boeing Co 737 planes, seeking to prevent pilot errors that over the years have caused fatal crashes of several jet and turboprop airliners. ()