US money market fund assets plunged by almost $70 billion over the weekly reporting period which included tax day for most Americans.

The outflow, the largest in two years, came on the heels of a historic cash influx as March’s banking sector turmoil served to turbocharge deposit flight in favor of high-yielding, short-term government obligations.

The exodus in the week to April 19 erased around 15% of the net inflow to money funds witnessed since the beginning of March.

Total money market fund assets dropped to $5.2 trillion. The drain was mostly from government funds, where the vast majority of recent inflows were concentrated, and was primarily attributable to institutional investors.

Obviously, the combination of tax week and the acute nature of the deposits-for-MMFs substitution effect in the wake of SVB’s failure makes it difficult to ascertain anything like a “clean” read on this week’s flows.

Thursday’s H.4.1 release showed reserve balances with the Fed dropped $182.6 billion, the the most in a year. Treasury’s cash balance rose by $178.5 billion. Some described the $108.5 billion influx on Tuesday amid tax payments as underwhelming.

Discount window usage rose over the week, as did borrowing from the Fed’s newly-created bank term funding facility.

Combined borrowing from the two backstops was almost $144 billion as of Wednesday.

Again, I should emphasize that some of these figures aren’t amenable to straightforward interpretation this week. “We believe this may have been a function of bank deposits declining due to individual tax payments,” TD’s Gennadiy Goldberg and Molly McGown said late Thursday, of the uptick in usage at the Fed’s emergency facilities.

“We will be watching bank deposit data in the next several weeks for further confirmation of deposit outflows, and we expect pressure on banks to persist in the coming months,” they added.