Henry established himself as a banker on Wall Street, became Director of the Equitable Life Insurance Company, and made eventually a fortune speculating on foreign currency exchange and railroads.
In
1867 Henry and his brother-in-law, Thomas Allen, bought a chief interest in St. Louis, Iron Mountain and Southern Railway which ran from St. Louis to southeast Missouri and to Arkansas and Texas.
The two were ultimately pushed out of their investment by Jay Gould, whose monopoly on the southwestern railroad system forced them to sell.
With a profit of one million dollars, Marquand effectively retired from the business world in 1880 and focused his energies on the acquisition of art and the management of the fledgling Metropolitan Museum of Art.
He was also the first honorary member of the American Institute of Architects.

Marquand was a member of the Provisional Committee of fifty men assembled in 1869 to establish a museum of art in New York City.
As a member of the building committee and president of the Museum's board of trustees, he witnessed the physical growth of the Metropolitan Museum of Art from various temporary quarters to its permanent home on the eastern edge of Central Park.
Marquand, a personal friend and client of museum architect Richard Morris Hunt, was in large part responsible for the realization of the project to extend and reorient the distinctive Beaux-Arts façade entrance east to Fifth Avenue, pushing for the plans to be carried out by Hunt’s son (Richard Howland Hunt) after the death of the renowned architect.
Marquand was also a significant contributor to the Museum's collection, particularly in the area of European paintings.
This donation included, among other old master works, Johannes Vermeer's Woman with a Water Jug, the first Vermeer to enter a United States collection and which scholars now agree is one of only thirty-seven known works by the artist.

Marquand was also a benefactor of the Metropolitan Museum of Art Schools and Princeton University, donating funds for the creation of the Bonner-Marquand Gymnasium and the Marquand Chapel (the latter designed by Richard Morris Hunt).
Henry established himself as a banker on Wall Street, became Director of the Equitable Life Insurance Company, and made eventually a fortune speculating on foreign currency exchange and railroads. In
1867 Henry and his brother-in-law, Thomas Allen, bought a chief interest in St. Louis, Iron Mountain and Southern Railway which ran from St. Louis to southeast Missouri and to Arkansas and Texas. The two were ultimately pushed out of their investment by Jay Gould, whose monopoly on the southwestern railroad system forced them to sell. With a profit of one million dollars, Marquand effectively retired from the business world in 1880 and focused his energies on the acquisition of art and the management of the fledgling Metropolitan Museum of Art. He was also the first honorary member of the American Institute of Architects.
Marquand was a member of the Provisional Committee of fifty men assembled in 1869 to establish a museum of art in New York City. As a member of the building committee and president of the Museum's board of trustees, he witnessed the physical growth of the Metropolitan Museum of Art from various temporary quarters to its permanent home on the eastern edge of Central Park. Marquand, a personal friend and client of museum architect Richard Morris Hunt, was in large part responsible for the realization of the project to extend and reorient the distinctive Beaux-Arts façade entrance east to Fifth Avenue, pushing for the plans to be carried out by Hunt’s son (Richard Howland Hunt) after the death of the renowned architect. Marquand was also a significant contributor to the Museum's collection, particularly in the area of European paintings. This donation included, among other old master works, Johannes Vermeer's Woman with a Water Jug, the first Vermeer to enter a United States collection and which scholars now agree is one of only thirty-seven known works by the artist.
Marquand was also a benefactor of the Metropolitan Museum of Art Schools and Princeton University, donating funds for the creation of the Bonner-Marquand Gymnasium and the Marquand Chapel (the latter designed by Richard Morris Hunt).
Henry Gurdon Marquand