McColgan boosted brokerage business

There’s a new name on the rise at the city’s financial powerhouse: Ellyn McColgan.

McColgan, who runs the brokerage arm of Fidelity Investments, took on a new title and greater responsibilities with yesterday’s shakeup. Though she has notched a series of successes in her 17 years at the financial-services giant, she hasn’t enjoyed the name recognition of the company’s other top managers.

That’s likely to change.

Yesterday’s move puts McColgan, 53, in charge of nearly half of Fidelity’s 42,000 employees. That’s considerably more than Abigail Johnson, also seen as a potential successor to her father, chairman Edward C. ‘‘Ned’’ Johnson III.

‘‘If there are other heirs apparent, they’re pretty much off everyone’s radar screen,’’ said John Bonnanzio of the independent newsletter Fidelity Insight.

McColgan expands her authority from Fidelity’s brokerage businesses to a collection of other divisions, including life insurance.

Though Fidelity is best known for its mutual-fund business, McColgan has built its brokerage arm into a force in the industry since taking it over in 2002.

The daughter of a New Jersey pipe fitter, McColgan was the first member of her family to go to college. She graduated from Harvard Business School before going to work at a Wall Street brokerage. She joined Fidelity in 1990.

When McColgan took the reins, brokerages were struggling with a stock market slump that had damped investor enthusiasm for playing the market. She slashed trading fees, overhauled the online-trading operation, and acquired companies to boost Fidelity’s ability to handle back-office trading for investment advisers. Since then, the number of daily trades has tripled, and the company now administers accounts worth $1.7 trillion — recently passing Merrill Lynch to take the top spot.

‘‘She’s built a powerhouse organization,’’ said Bonnanzio.

In an organization known for its reserve and low public profile, McColgan has embraced the role of a public leader, speaking at conferences and women’s business groups. She also holds a handful of philanthropic seats in Boston, serving as an overseer of the Museum of Fine Arts and on an advisory board at Massachusetts General Hospital.