Money market mutual fund assets decreased by $12.25 billion to $2.53 trillion, in the week that eneded July 18.

Retail investors close to steady at $885.8 billion, a decrease of $390 million. But institutional investors pulled $11.9 billion out of money funds.

Since the beginning of March, institutions in fact have pulled $74.4 billion from money funds, according to ICI statistics.

The pullout comes as the Securities and Exchange Commission weighs a second round of post-credit crisis reforms of the money fund industry.

The federal regulator is considering a proposal to let the net asset value of shares in such funds fluctuate daily. A stable $1 a share value has been a bedrock of the industry, helping money funds compete with banks for deposits by large institutions.

A second proposal may be a combination of capital buffers and limits on redemptions. The staff of the New York Federal Reserve Bank Thursday indicated it was in favor of a limit on money fund withdrawals.

The ICI, which represents the mutual fund industry, opposes both proposals.

A floating net asset value “will undermine the core features of money market funds that investors seek—stability, liquidity, and convenience,’’ contends ICI’s chief executive Paul Schott Stevens. “They will drive retail investors back to the fixed, low rates paid by banks…institutional investors to less regulated, higher-risk alternatives…and fund companies out of the business.’’

And capital buffers?

”The cost of building or paying for capital buffers would come from investors’ yields—yields that have been near zero for more than 30 months,’’ in his view.

A first set of reforms came in 2010, in the wake of the “breaking of the buck” – the $1 a share net asset value – by the Reserve Primary Fund. That came in September 2008, as Lehman Brothers went under in the eruption of the mortgage-backed credit crisis.

The Reserve fund found itself holding too many Lehman Brothers assets that plunged in value.

Total net assets of money market mutual funds have fallen 33.7% since the end of 2008 to $2.54 trillion, according to ICI’s statistics.