Gov. Gavin Newsom's proposed $322.2 billion budget includes a $228.9 billion general fund, $16.9 billion in reserves and no plans to raise taxes.
"'The market environment will likely become a bit more difficult in the coming week, as supply will jump to its highest level in weeks, while dealers are heavier than average," said Mikhail Foux, head of municipal research and strategy at Barclays.
The management team sees opportunity in pockets that other investors avoid, like American Dream, Midwestern private colleges and senior living facilities.
The rating agency said the district's strong management helped boost its ratings ahead of an $806 million bond issuance slated for Jan. 22.
Wiles retired from Los Angeles County at year-end but will still influence the industry as a member of the Municipal Securities Rulemaking Board.
Analysts cited growth in the county's reserves, conservative budgeting and strong sales tax revenue as the county prepares to sell GO bonds.