By Ross Kerber BOSTON Vanguard Group Inc reallocated expenses on a $1.9 billion municipal money market fund, a spokesman said, a move akin to the fee waivers that rivals have granted. Because of Vanguard's client-owned structure it cannot simply waive fees and cover them, the industry's traditional method of protecting investors from low interest rates. Instead, as yields fall below expenses on the Vanguard Pennsylvania Municipal Money Market Fund, "expenses of the fund are being temporarily reallocated to other funds within Vanguard," company spokesman Freddy Martino said via e-mail. Vanguard, the world's largest mutual fund manager with some $6 trillion in assets, said in a securities filing late on Monday that it made the change "to maintain a zero or positive yield for the fund." Vanguard is not currently reallocating expenses on other funds, Martino said via e-mail. He also said the reallocated expenses are insignificant in the scale of Vanguard's fund line. "We therefore do not expect this change to increase expense ratios for any of our other funds," he said. The yield on the benchmark 10-year U.S. Treasury note, around 2% at the start of the year, has fallen sharply amid the COVID-19 pandemic and was at 0.6677% at midday Tuesday. Fee waivers were common during the financial crisis and have returned of late. Federated Hermes (NYSE:FHI) Inc, another large money fund sponsor, said June 26 it reduced fees or payments on 16 funds and trusts "due to current market conditions." A Federated spokesman said it has not outlined what impact the waivers may have on its financial results. Lower rates also have led Vanguard and rivals to close some money funds to new investors as a way to protect returns for existing ones. Daniel Wiener, who edits a newsletter for Vanguard investors, said Vanguard's action shows how it has many options for deciding how it charges investors for its products. "In the scheme of things the reallocated costs are minuscule in comparison to the overall costs but what it tells you is that there is lots of flexibility," he said.