Bank of New York Mellon has agreed to pay $3 million to settle an investigation into its handling last year of a major software system crash.

The Massachusetts Securities Division had investigated BNY Mellon for what it said was the bank's failure in August to calculate net asset values on about 1,200 mutual funds. The incident arose after a BNY Mellon tech vendor, SunGard, suffered a total system outage.

"Financial institutions like BNY Mellon are expected to oversee their third-party vendors and have backup plans if the vendor's system fails," William Galvin, the Massachusetts secretary of the commonwealth, said in a news release Monday.

BNY Mellon's lack of a backup plan "caused untimely and nonuniform information to be sent to the funds, as well as an unbalanced distribution of information to clients," Galvin said.

BNY Mellon did deliver net asset values to the mutual funds on Aug. 24, using alternative methods to calculate the values, said Kevin Heine, a BNY Mellon spokesman.

"While we truly regret any confusion our clients may have experienced during the initial hours of the outage, the fact remains that Bank of New York Mellon took decisive action during an unprecedented vendor failure to protect our clients' interests and deliver daily net asset values to the funds, in accordance with their instructions," Heine said.

BNY Mellon also agreed to make changes to its internal controls and supervisory procedures. Several enhancements to the bank's procedures for calculating net asset values have already been made, Heine said.

SunGard remains BNY Mellon's vendor for calculating net asset values, Heine said.