The blowout U.S. jobs report for October means the Federal Reserve may be weeks away from raising interest rates. For U.S. savers earning next to nothing on $2.6 trillion of money-market mutual funds, the move will barely register.

The reason is that there's an unprecedented shortfall in the safest assets, especially Treasury bills — a mainstay of money funds and traditionally the government obligations that are most sensitive to changes in Fed policy. The shortage means some key money-fund rates will probably remain near historic lows even if the central bank increases its benchmark from near zero next month.

The phenomenon is a consequence of regulators' efforts to curb risk after the financial crisis. Money-market industry rules set to take effect in October 2016 may lead investors and fund companies to shift as much as $650 billion into short-maturity government obligations, according to JPMorgan Chase & Co. Meanwhile, the amount of bills as a share of government debt is the lowest since at least 1996, at about 10 percent, and the Treasury is just beginning to ramp up issuance of the securities after slashing it amid the debt-ceiling impasse.