(Bloomberg News) Michel Moreno, the 42-year-old chief executive officer of the Moreno Group, an oil-services company, has been investing the cash he set aside during the financial crisis in the most well-known U.S. companies.

"If I'm going to have market exposure, I want to focus on the area I'm personally more comfortable with, which is large-cap stocks," he said.

Investors like Moreno are buying shares of the biggest U.S. companies again as the market returns to levels not reached since 2008 and the municipal bond market has become more volatile. GenSpring Family Offices, whose average account size is about $30 million, has moved about $1.5 billion, or nearly 10% of clients' assets, into stocks of large dividend-paying companies during the past three months.

"Wealthier folks are beginning to look at this as a market that they can be opportunistic buyers in," said George Walper, Jr., president of Chicago-based Spectrem Group, a consulting firm that tracks attitudes among millionaires. "They're still much more cautious than they were in 2005 and 2006, but it's starting to turn around," he said.

More than half of investors with $5 million to $25 million in investable assets said they will probably buy stocks in 2011, according to a February 22 survey by Spectrem.

Investors put $5.2 billion into mutual funds that invest in the largest U.S. companies in January, the biggest monthly inflow since April 2009 and a reversal from the $13 billion in outflows in December, according to data from Morningstar Inc. In all of 2010, investors withdrew $77 billion from large company funds, said Morningstar, a Chicago-based research firm.

Overdue For Gains

Shares of U.S. companies such as Coca-Cola Co. and Johnson & Johnson are overdue for gains and represent the most attractive part of the market, according to Jeremy Grantham, chief investment strategist for Boston-based Grantham, Mayo, Van Otterloo & Co., which manages $107 billion on behalf of institutions. Johnson & Johnson returned 4.4% and Coca- Cola returned 17% in the six months through February 23.

"These stocks are not just a little cheap, they are almost as cheap as they ever get, relative to the rest of the market," said Grantham, who accurately predicted the 2009 market bottom.

The largest U.S. companies, as measured by the Standard & Poor's 100 Index, returned 13% in 2010 compared with 27% returns for small U.S. stocks in the Russell 2000 Index. The S&P 100 had a price-earnings ratio of 14 compared with a ratio of 31 for the Russell 2000 on Feb. 23. Price-earnings ratios represent the price investors pay for each dollar in annual earnings-per-share. A low ratio may indicate a stock is undervalued.