The assets of the nation’s mutual funds were flat in December, gaining $12.3 billion. 

That worked out to a gain of one-tenth of a percent, for an industry that has $11.6 trillion in combined assets, according to the Investment Company Institute.

The big losers were long-term funds. Stock, bond, and hybrid funds had a net outflow of $16.48 billion in December, compared to an outflow of $4.45 billion in November.

Stock funds saw an outflow of $28.79 billion in December, compared with an outflow of $18.61 billion in November 

Hybrid funds posted an inflow of $2.75 billion in December, compared with an outflow of $4.86 billion in November.

Bond funds had an inflow of $9.56 billion in December, compared with an inflow of $19.02 billion in November.

The big gainer: Money market funds, with an inflow of $38.52 billion in December, compared with an inflow of $43.13 billion in November.

Funds offered primarily to institutions had an inflow of $29.10 billion. Funds offered primarily to individuals had an inflow of $9.42 billion.

For all of 2011, $130.3 billion was pulled out of stock funds. Investors added $136.5 billion to taxable bond funds. And took $11.8 billion out of municipal bond funds.

Tom Steinert-Threlkeld writes for Securities Technology Monitor.

Tom Steinert-Threlkeld is editorial director of the Money Management Group at SourceMedia. He oversees the Web and print operations of Money Management Executive, Mandate Pipeline, and Securities Technology Monitor. He also advises the Web operations of FInancial Planning, On Wall Street and Bank Investment Consultant. He was vice president of the Enterprise Group of Ziff Davis Media, where he founded Baseline magazine and was editor of Interactive Week. He also has extensive background in metropolitan daily news at The Dallas Morning News and the Fort Worth Star-Telegram in Texas. More recently, he served as editorial director of Broadcasting and Cable as well as Multichannel News magazines for Reed Business Information.