(Adds Bonddesk data)
May 17 (Reuters) - U.S. municipal bond funds reported $805 million of net inflows in the week ended May 16, slowing from $901 million in the previous week, according to data released on Thursday by Lipper.
With the exception of only three weeks, municipal bond funds have had positive flows since the start of September 2011.
As money kept flowing into muni bond funds, the four-week moving average was positive at $653 million, said Lipper, a unit of Thomson Reuters.
High-yield muni funds reported net inflows of $228 million, down slightly from $258 million in the week ended May 9, while flows into exchange-traded muni funds fell to $41 million from $104 million in the previous week.
BondDesk Group data for the week ended May 16 showed retail investors bought 2.0 bonds for each one they sold, down from the 2.1 ratio in the previous week.
The total number of bonds bought was 61,577, while the number of bonds sold was 30,714. The data is based on odd-lot customer transactions. (Writing by Tiziana Barghini; Editing by Dan Grebler and Andrew Hay)