Harvey Pitt, a authorized wunderkind who lasted simply 18 months as chairman of the Securities and Exchange Commission underneath President George W. Bush, died on Tuesday in Washington. He was 78.

His demise, in a hospital, got here after a sudden sickness, in accordance with his household, which didn’t specify the ailment.

Mr. Pitt’s profession had three consecutive legs, any one among which alone might need been the top on a lesser résumé. He started his profession on the S.E.C. and was promoted to normal counsel at age 30, the youngest ever to realize that rank. After solely three years, he left to characterize company shoppers for the highly effective legislation agency Fried Frank. There, rising to managing associate within the agency’s Washington workplace, he helped it turn out to be vastly worthwhile.

He returned to the S.E.C. as chairman in 2001, after crusing via a unanimous affirmation vote by which Sen. Charles Schumer, Democrat of New York, referred to as him “the Zeus of the field.” Not lengthy after, Mr. Pitt grew to become considerably of a family title for overseeing the swift reopening of U.S. inventory exchanges after the assaults of Sept. 11, 2001.

His reputation dipped, nonetheless, amid a collection of company accounting scandals — most famously on the power big Enron — that drew renewed consideration to his prior company work. Representatives of each events questioned his curiosity in investigating private-sector wrongdoing.

The remaining straw got here when it emerged that he had failed to inform the White House or his fellow S.E.C. commissioners that an accounting board chairman he championed had headed the audit committee of an organization accused of fraud. Under strain, Mr. Pitt resigned on election night time 2002.

Born on Feb. 28, 1945 in Brooklyn, Harvey Lloyd Pitt was the kid of Morris and Sara Pitt. His father was a vp of the Waldbaum’s grocery store chain; his mom was a homemaker.

Harvey, a Brooklyn Dodgers fan who was gutted when the staff left for the West Coast, his household mentioned, went on to earn levels from Brooklyn College and St. John’s University earlier than becoming a member of the S.E.C. straight out of school. It was the one job he had ever needed.

In 1978, with a rising household, he went into personal apply, the place he represented a few of the identical folks his group had been charged with regulating. His shoppers included Ivan Boesky, who pleaded responsible to insider buying and selling in the course of the junk bond scandal of the late Nineteen Eighties, and scores of economic corporations.

Such was his fame that when Mr. Pitt’s personal agency landed in a minor authorized spat, his hiring of the then-smaller rival agency Williams & Connolly made waves.

“It was notable that if Harvey Pitt had confidence in us, others would easily follow, and they did,” mentioned Brendan Sullivan, a Williams & Connolly senior associate.

At his affirmation listening to, Senator Phil Gramm, Republican of Texas, supplied a tweak on a track lyric from the British rock band Hermit’s Hermits: “Harvey Pitt has seen it from both sides.”

Inside the fee, he was indefatigable, mentioned Cynthia Glassman, a former commissioner. After the group obtained Blackberry smartphones for the primary time, she mentioned, Mr. Pitt grew to become “big on emails — especially in the middle of the night.”

He took a lighter method to S.E.C. enforcement than did his predecessors, telling Congress that he would “repair relationships that have been harmed in the past.” That perspective proved untenable within the wake of Enron and different scandals.

“Your choice of words sends the wrong message to auditors, to the S.E.C. staff and to the investing public,” Rep. John Dingell wrote to Mr. Pitt a couple of weeks after Enron’s collapse.

Morale within the company dropped precipitously throughout Mr. Pitt’s tenure, and a slew of senior workers departed.

His fall in stature was summarized by a New York Times headline on the day in 2003 that his successor, William H. Donaldson, was confirmed: “S.E.C. Choice Says He’s No Harvey Pitt.”

But mates and former colleagues mentioned Mr. Pitt had been unjustly criticized. The former S.E.C. normal counsel David Becker recalled being on the telephone with Mr. Pitt when the true property developer Donald J. Trump referred to as to complain about Trump firms being investigated for fraud.

“Harvey politely explained that he was not in a position to help, since he had added to the division’s proposal the very fraud allegation about which Trump was calling to complain,” Mr. Becker mentioned.

Mr. Pitt’s first marriage, to Phyllis Kay, resulted in divorce in 1981. He married Saree Ruffin in 1984. He is survived by his spouse; two daughters, Emily Pitt and Sally Pitt Plowden; two sons, Jonathan and Rob; and three grandchildren.

In the years that adopted his S.E.C. chairmanship, Mr. Pitt hardly receded from public view. He continued to weigh in on regulatory points, sometimes contributing opinion articles to The Wall Street Journal.

His most recent column took a pointy view of recent proposed S.E.C. guidelines on personal funding funds.

“Too often, regulatory demands make it difficult or impossible for new entrants to gain traction in an industry,” Mr. Pitt wrote. “There is often no voice at the table representing the interests of that segment of the industry.”