Image copyright Reuters Image caption The statue is part of a campaign to encourage companies to act against gender inequality

Tourists visiting New York's Wall Street today may get a surprise.

A statue of a young girl has been placed in front of Wall Street's iconic bull, to call attention to gender inequality and the pay gap in the corporate world.

The statue was commissioned by one of the world's largest fund managers. It says the girl represents the future.

One in four of the 3,000 largest traded US companies do not have even one woman on their board, the company says.

State Street Global Advisors (SSGA), a $2.5 trillion (£2.06 trillion) asset manager, said it would send a letter to 3,500 companies asking them to act.

It argued that companies with more female leaders performed better.

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"A key contributor to effective independent board leadership is diversity of thought, which requires directors with different skills, backgrounds and expertise," SSGA president Ron O'Hanley said in a statement.

"Today, we are calling on companies to take concrete steps to increase gender diversity on their boards and have issued clear guidance to help them begin to take action."

SSGA said it would act to ensure that measures to address inequality are being taken, including using its votes in company's boards.

But the company has had its own issues in implementing diversity. According to Reuters, only three of its 11 board members are female, and two of them have been serving for more than a decade.

Image copyright Reuters Image caption The company says it wants the statue to stay for at least a month

Wall Street's Charging Bull statue was originally guerrilla art by Italian-born artist Arturo Di Modica. Installed in 1989, the bronze sculpture was meant to represent the "strength and power of the American people" in response to the market crash in 1987.

But it become a popular attraction and was allowed to stay.

Unlike the bull, the girl statue, by artist Kristen Visbal, has been given a permit by the city's authorities.

It is not clear how long the statue will remain there. The company wants it to stay for a month, but says it will be happy if it becomes a permanent feature.