New York City is one of the largest issuers of municipal bonds in the country, and its regular trips to the market have become a real-time referendum on its fiscal health. The city is borrowing heavily to fund transit, schools, and climate resilience.

Investors have so far shown steady appetite, though analysts at the fictional firm Battery Fixed Income warn that rising debt service and pension costs bear watching. The interest rates the city pays reflect the market's confidence, or lack of it, in its budget.

For ordinary New Yorkers, the arcane world of muni bonds has concrete stakes: it determines how cheaply the city can build. A strong reception keeps borrowing costs down; a wary one makes every project pricier.