[2] Following the difficult years of the Great Depression, Paine Webber merged with Jackson & Curtis, another Boston-based brokerage firm, in June 1942.

With its greater combined asset base, Paine Webber Jackson & Curtis had become a significant participant in the New England financial market.

In October 1960, Paine Webber managed the initial public offering (IPO) of the Green Shoe Manufacturing Co.,[4] in which it introduced the concept of stabilization covered by an overallotment option,[5] which has ever since been known by the colloquial name of greenshoe.

The firm's holding company was incorporated on June 30, 1969, as PaineWebber Inc., of which Paine Webber Jackson & Curtis[3] was its main subsidiary.

PaineWebber also acquired Abbott, Proctor & Paine in 1970, the Abacus Fund, a closed-end investment company in 1972, Mitchum, Jones & Templeton Inc. in 1973.

[8] In 1986, the firm opened a new technology and transaction processing operation at Lincoln Harbor in New Jersey.

[9] In 1995, PaineWebber completed the acquisition of the brokerage and investment banking firm Kidder, Peabody & Co. from General Electric Company.

During these years Michael G. Ricciardi was the managing director and head of global fixed income sales at Paine Webber.

[13] The deal was not profitable for PaineWebber, as a great number of brokers left the firm due to corporate cultural differences, taking their clients with them.

[14] On November 3, 2000, under the leadership of chairman and CEO, Donald Marron, the company completed a US$10.8 billion cash and stock merger with UBS, a banking conglomerate headquartered in Zurich, Switzerland.