Long-term mutual funds saw the biggest net inflows in April since February 2007. According to estimates released Wednesday by Strategic Insight, investors put nearly $20 billion into stock and balanced funds and more than $30 billion into bond funds (these figures exclude ETFs but include VA funds).

So far in 2009, according to the research and consulting firm, net inflows to stock and bond funds exceeded $50 billion year-to-date, despite economic conditions.

Benefitting from the recovery of the stock and credit markets lately, assets managed in the U.S. mutual fund industry – including open- and closed-end funds and VA funds, but excluding ETFs – once again exceed $10 trillion, for the first time since September 2008, after expanding more than $500 billion since the end of March.

The trend of net inflows into stock and bond funds began in the last week of March, following an upturn in stock markets. Strategic Insight says April’s notable recovery was the clearest sign so far this year that investors have regained a measure of confidence in both equity and credit markets.

“U.S. mutual fund shareholders, most of whom are buy-and-hold investors, have been waiting for an opportunity to get back into the markets. Putting billions of dollars back into stock and bond funds in April is a strong vote for mutual funds as a preferred way to invest and save for most households,” said Avi Nachmany, SI’s director of research in a released statement.