Money market funds attracted nearly $40 billion in new cash in the week to August 16, data released late Thursday in the US showed.

It was the largest haul since July 5, and extended the run of inflows to five weeks.

Total assets touched a new record near $5.57 trillion.

The lion’s share of the influx was attributable to institutional government, although retail investors plowed a sizable $11 billion into government money funds too.

Minutes from the July FOMC meeting found the SOMA manager noting that a “possible further reduction in policy uncertainty… could incentivize money funds to extend the duration of their portfolios,” where that means rotating out of RRP to soak up T-bill supply. Ironically, the minutes actually increased policy uncertainty at the margins as market participants focused on the prospects for additional rate hikes.

Whatever the case, Treasury has had no trouble finding buyers. “Demand remains particularly strong for bill auctions despite the surge in the auction sizes as the front-end remains awash in cash, as evidenced in part by daily RRP demand that has steadied close to $1.8 trillion this month,” Oxford Economics’s John Canavan wrote.

Note that primary dealers’ bill holdings were just $44.7 billion as of last week. That was the lowest since early May, and just a third of the all-time high recorded during the week of July 12.

The implication appears to be that someone other than money market funds is buying bills.

Remember: Not everyone has access to the RRP garage. To those investors, 5.28% (where Treasury sold bills on Thursday) probably looks pretty good. The RRP offering rate is just two basis points higher.

Meanwhile, usage of the Fed’s bank backstop established in the wake of SVB’s failure rose to $107.242 billion in the week to Wednesday, the latest update revealed.

That’s another new record. Discount window usage rose slightly.

Total borrowing from the Fed’s backstops was $109.21 billion. That figure has increased every week but one since April.