Investors piled into muni bond mutual funds this past week.

Muni bond funds saw $459 million of inflows from funds that report their flows weekly for the week ended April 25, according to Lipper FMI.

In fact, funds saw their highest inflow numbers in a month. In the previous week, which ended April 18, there were net inflows of $159 million. The market has now seen positive flows for 31 out of the past 34 weeks.

Munis had a week of shifting and moderate demand in both the primary and secondary markets. Issuance is estimated to have fallen, and investor demand for volume diminished as the week progressed.

Tax-exempt yield performance since last Friday equaled that of Treasuries at the short end and bettered it at the long end. But the Treasury yield bested its tax-exempt equivalent in the 10-year part of the curve.

This week, assets for funds that report their flows weekly rose to $292.9 billion from $291.3 billion the previous week.

The value of the holdings for weekly reporting funds rocketed by $865 million. The week before, they jumped $413 million.

The four-week moving average for all municipal bond mutual funds that report their flows weekly experienced a $156 million inflow, up from a $149 million gain the week before.

High-yield muni funds remained popular with investors. They have been positive for 19 of the previous 20 weeks.

Funds that report weekly saw $202.1 million in inflows, Lipper said. The previous week, high-yield funds reported $124.2 million in inflows.

Assets for high-yield funds that report their flows weekly rose to $38.64 billion, up slightly from $38.26 billion the previous week.

The value of the holdings for weekly reporting funds increased by $181 million. Last week, they rose by almost $101 million.

The four-week moving average for all high-yield muni bond funds that report their flows weekly was a $129 million inflow, up from a $103 million inflow the week before.