The city could see millions in savings following a major credit rating agency’s decision to upgrade New York City’s bond rating yesterday, the third such agency to do so in the past six weeks.

The new Aa3 rating, the fourth-highest available from Moody’s Investor Service, comes at a time when the fiscal future of New York is shining bright, as a soaring real estate market, a booming financial sector, and a mayoral administration reticent to spend its surpluses have won the hearts of lenders.

The rating upgrade marks the first time in history that all three major rating agencies have given the city a rating in the upper-tier “AA” category, according to the city.

A higher bond rating traditionally translates into slightly lower interest rates for the city’s debt, which can result in millions in savings given the tens of billions of dollars the city has in outstanding bonds.

“New York is stronger than ever, and Wall Street has once again recognized our success,” Mayor Bloomberg said in a statement.

Moody’s credited conservative budgeting and a diverse economy fueled by Wall Street. However, the Bloomberg administration’s projections show deficits in the city’s budget as early as 2009, a point Moody’s noted in a statement on the rating upgrade.

The new rating comes less than three weeks after rating agency Fitch upgraded the city to its fourth-highest bond rating, AA-, and six weeks after Standard & Poor’s awarded New York City its third-highest rating, AA.

In the financially stressed times of the 1970s, the city’s fiscal credibility was so low that it lacked a bond rating. Since, its integrity has slowly climbed, with some ups and downs, to a point where it nears the highest rating available.