Updated from 9:38 a.m. EDT

The April 15 income tax deadline helped mutual fund inflows rise for the fourth straight week, as AMG Data Services reported that $1.4 billion found its way into equity mutual funds in the most recent week despite stock market declines.

Trim Tabs, another fund-flow tracking company, reported equity inflows of $1.6 billion, with $1.2 billion of that going into domestic equity funds.

April is historically a month that shows high inflows, particularly because many investment decisions need to be made ahead of investors' annual income tax filings.

"It's tax-avoidance investing," said Charles Biderman, chief executive of the Santa Rosa, Calif., company. "Money goes into IRAs and companies have to make their pension contributions before the deadline."

According to AMG data, equity funds have seen four consecutive weeks of net inflows since late last month, reversing a spate of net outflows triggered by the bombing of commuter trains in Madrid on March 11.

Biderman said equity funds saw $2.5 billion in net inflows in the week ended April 7, for a total inflow of $4.1 billion over the nine business days covered by the surveys.

Totals would likely have been higher, but a law passed last week gave companies more leeway in calculating their mandatory pension contributions and eased the burden for big corporations, mostly airlines, steel producers and other large industrial companies.

"If Congress hadn't passed that law last week, you'd have seen higher totals," Biderman said. "It reduced the estimated pension contributions $10 billion from $20 billion. Some of that goes into mutual funds."

The AMG survey showed about $930 million going into international securities; every global equity sector besides Latin America reported net inflows for the week.

Real estate funds saw net outflows of $446 million, AMG reported.

More from Mutual Funds

60 Seconds: What's the Difference Between an ETF and a Mutual Fund?

60 Seconds: What's the Difference Between an ETF and a Mutual Fund?

Mutual Funds on Track for Record Year

Mutual Funds on Track for Record Year

Bitcoin Today: Prices Come Off Highs as Rally to $10,000 Pauses

Bitcoin Today: Prices Come Off Highs as Rally to $10,000 Pauses

Video: How to Select Mutual Funds in Your 401(k)

Video: How to Select Mutual Funds in Your 401(k)

Tax Tip: Uncle Sam Will Be Looking for Your Cryptocurrency Trades

Tax Tip: Uncle Sam Will Be Looking for Your Cryptocurrency Trades