BNY Mellon Corp's computer glitch this week disrupted pricing on nearly 5 percent of U.S. mutual funds and exchange-traded funds, according to data from Morningstar Inc and Lipper Inc.

On Wednesday, for example, 1,307 mutual funds and ETFs had disrupted pricing, or 4.5 percent of the 28,812 funds that have net asset value calculations, according to Morningstar and Lipper.

Problems with mutual fund pricing appeared to have escalated from 33 funds on Monday to 821 on Wednesday, according to Morningstar. BNY Mellon said on Friday it still does not know when the problems with mutual fund pricing will be fixed.

An accounting system BNY Mellon uses to calculate fund values collapsed last weekend during an upgrade conducted by financial services software provider SunGard.

In an update on Friday morning, BNY Mellon said it continues to experience performance problems with SunGard's InvestOne system. Processing the Wednesday prices for mutual funds, for example, continues to be delayed.

"We do not have an ETA for completion at this time," BNY Mellon said in an update on its website. "We will continue to work with our clients and utilize the agreed upon fair value and other contingency measures until normal processing can resume."