Maryland Lt. Gov. Anthony G. Brown. (Photo by Astrid Riecken For The Washington Post)

Maryland Lt. Gov. Anthony G. Brown (D) changed his state biography in recent days to reflect a previously unlisted five-month stint with the giant wealth-management firm Merrill Lynch about 15 years ago.

Aides to Brown, a leading candidate for governor this year, characterized the move as a correction of an innocuous oversight that was discovered after reporters sought a timeline of his work history as part of their campaign coverage.

But a spokeswoman for the rival Democratic campaign of Attorney General Douglas F. Gansler on Monday called the change “extremely troubling” and accused Brown of “trying to pull the wool over voters’ eyes” about a part of his background.

In one of Brown’s television ads, the narrator tells viewers that “when many of his generation chose Wall Street, Anthony chose military service.”

“He clearly was pursuing a career as a stockbroker,” Gansler spokeswoman Katie Hill said. “He’s spinning a completely different tale in his campaign ads.”

Brown’s five months with Merrill Lynch, at a facility in Greenbelt, came about 15 years after he graduated from Harvard University with a bachelor’s degree.

In the meantime, Brown had served five years of active duty in the U.S. Army and 10 years in the Army Reserve. He also had obtained a law degree from Harvard, worked four years at the Washington law firm of Wilmer Cutler & Pickering, and was elected to the House of Delegates representing a Prince George’s County district.

Brown campaign manager Justin Schall characterized Brown’s time with Merrill Lynch as a brief career detour before he returned to law work at another area firm, Gibbs & Haller, in 2000.

“Anthony was in a short, five-month training program in Greenbelt and upon completing it, decided it just wasn’t the right path for him,” Schall said.

Maia Hunt Estes, Brown’s chief of staff in his government office, said small discrepancies in Brown’s biography were discovered after reporters requested a detailed work history. Brown’s starting date with Gibbs & Haller had been incorrectly listed as 1998, and Merrill Lynch was not listed.

Estes said there was “absolutely not” any attempt to conceal Brown’s employment with Merrill Lynch.

She pointed to an annual financial disclosure form that Brown was required to fill out as a delegate.

A form filed in 2000 notes that between April 19 and Sept. 24 of 1999, “I was employed as a financial consultant with Merrill Lynch in the Greenbelt, MD, office.”