In January 1946 he formed Rockefeller Brothers, Inc., one of the first postwar venture-capital operations, starting with a capitalization of $1.5 million.

There were eight partners in all, the five brothers and their sister, Abby, and two non-family members, Harper Woodward and MIT scientist Ted Walkowicz.

His investment interests included the fields of aviation, aerospace, electronics, high temperature physics, composite materials, optics, lasers, data processing, thermionics, and nuclear power.

These include: Intel, Apple,[1] AppNexus, Astranis, StrataCom, Check Point Software, Dapper Labs, DoubleClick, 3Com Corporation, Mosaic, PGP, Itek, Digex, Interos,[5] Shape Security, Phoenix, Second Rotation (gazelle), RedSeal, CTERA Networks, and Juno Therapeutics.

It also has a significant venture in the nascent nanotechnology field, with early funding of Nanosys and the nanotech division of Du Pont.