County Treasurer-Tax Collector Dan McAllister said San Diego County’s investment pool, which invests the reserve accounts for some 100 local government agencies and school districts, received Standard & Poor’s highest ratings for the 13th consecutive year.

The pool of funds, which reached a record $7.4 billion earlier this year, was rated AAAF for credit quality and S1 in volatility by S&P, each the best, McAllister’s office said.

“We owe it to our fund participants and to the entire county to be the best,” he said.

Because the fund invests only in the safest instruments, the annualized returns are meager, but a positive 0.43 percent.

In addition to a team of full-time investment professionals, the fund is overseen by a 10-member oversight committee made up of county, school and special district officials, and five public members.

— Mike Allen