The firm was founded in San Francisco, California in 1914 by Charles R. Blyth and Dean G. Witter.

Eastman Dillon Union Securities & Co. established a successful track record during the 1940s and 1950s in as a merchant banking firm, focusing on acquiring and restructuring companies.

The merger would prove difficult for the combined company which struggled to integrate Blyth Eastman's investment banking operations with Paine Webber's retail business.

This merger never fully achieved the intended goal of turning Paine Webber into a major investment banking house.

[4] In 1984, a reorganization of the company combined the three subsidiaries, Paine, Webber, Jackson & Curtis; Blyth Eastman Paine Webber; and PaineWebber Mitchell Hutchins, under one name, PaineWebber Incorporated, resulting in the disappearance of the Blyth Eastman brand.