Diamond Shamrock

Diamond Shamrock

Logo used from 2001 to 2021
Formerly	Diamond Shamrock Corporation (1967–1987) Diamond Shamrock R&M Inc. (1987–1990) Diamond Shamrock Inc. (1990–1996) Ultramar Diamond Shamrock Corp. (1996–2002)
Company type	Public (1967–2001) Brand (2002–2005; 2021–present)[citation needed]
Traded as	DRM (1987–1996)[1] UDS (1996–2001)[2]
Predecessor	Diamond Alkali Shamrock Oil Sigmor Corp.
Founded	December 1, 1967; 56 years ago (1967-12-01) in Cleveland, Ohio U.S.
Defunct	January 2, 2002 (2002-01-02)[3]
Fate	Acquired by Valero Energy, remaining as a brand
Successor	Valero CST Brands (convenience store network)
Headquarters	1 Valero Way, San Antonio, Texas , United States
Area served	North America
Products	Gasoline convenience store Select locations truck stops car wash repair shop
Brands	Stop-N-Go
Owner	Valero Energy Corporation
Divisions	Corner Store
Website	valero.com

Diamond Shamrock (formerly known as the Ultramar Diamond Shamrock Corporation) is an American brand of gasoline stations under the ownership of the Valero Energy Corporation and is currently headquartered in San Antonio, Texas. The former company was established on December 1, 1967 when Cleveland-based Diamond Alkali merged with Shamrock Oil of Amarillo, Texas, creating the entity known as the Diamond Shamrock Corporation.^[4]

The venerable company was the nineteenth largest energy company in the United States in 1985^[5] and had operations in nineteen states, but had a massive presence in the states of Oklahoma, Colorado, Texas, New Mexico, and Ohio, with a notable presence within certain markets of California and New York. Diamond Shamrock also owned and operated its well-known convenience store chain Corner Store, that became the predecessor of the chain CST Brands Inc. (succeeded by Circle K in 2017).

In May 1979, Diamond Shamrock announced that it would be moving its corporate headquarters from the crime-stricken Cleveland, Ohio to Dallas, Texas in an effort to improve the company’s image and reputation.^[6] Looking to expand its presence, the USD$160 million acquisition of the Sigmor Corporation in July 1982 added 600 more stores to Diamond Shamrock’s portfolio of locations and also as a dividend, it received ownership of the Three Rivers oil refinery located between San Antonio and Corpus Christi, Texas.^[7]

February 1987 saw the detachment of Diamond Shamrock’s production and exploration branch and would rename itself to the Maxus Energy Corporation once the split from its refining and marketing division took effect. Concurrently, Diamond Shamrock’s own refining and marketing division was also renamed as Diamond Shamrock R&M Inc. and would trade under DRM on the New York Stock Exchange. The split subsequently made Maxus Energy (NYSE: MXS) the largest energy company in the United States during that time.^[1]

In November 1995, it was announced that Diamond Shamrock would acquire Houston-based National Convenience Stores Inc., who operated business under the Stop-N-Go nameplate for USD$260 million,^[8] ruining Circle K’s opportunity to acquire the chain for themselves after their bid for USD$232 million.^[9] In September 1996, it was announced that Diamond Shamrock would be acquired by Montreal-based Ultramar, a Canadian oil company for USD$1.96 billion. The primary reason for the merger was originally to attain USD$75 million in annual savings, according to Roger Hemminghaus, the chairman of the newly combined companies Ultramar Diamond Shamrock. The Ultramar and Diamond Shamrock merger would also skyrocket the company to become the third-largest in gasoline refining and marketing corporation in the United States and would also increase Diamond Shamrock’s locations to more than 4,400 stores.^[10] In April 1997, it was announced that Ultramar Diamond Shamrock would be acquiring the U.S. operations of Total Petroleum N.A. for an estimate of USD$400 million, alongside their USD$414 million in debt.^[11]

In May 2001, it was announced that the Valero Energy Corporation had agreed to acquire Ultramar Diamond Shamrock for USD$4 billion, a deal that would make Valero Energy the second-largest oil refiner behind ExxonMobil.^[12] The acquisition was approved by the Federal Trade Commission on December 19^[13] via an approval of a consent decree and was finalized and completed on January 2, 2002, ultimately ending the company’s operations. The merger of UDS and Valero would encompass a convenience store network of more than 5,000 stores and twelve refineries.^[3]

In July 2005, Valero Energy announced that it would be phasing out the Diamond Shamrock brand and convert its remaining 2,900 locations to the Valero name. Prior to this, the conversion of Diamond Shamrock stores had already started with the east and west coasts of the United States. The conversion would cost Valero Energy roughly USD$70 million and would take a little over two years to complete its conversion of over 1,030 stores and 830 branded wholesale sites. Despite the announcement, the remaining Diamond Shamrock locations would not be renovated and converted until 2006.^[14]

As of 2024, the Diamond Shamrock brand is still actively being in use by Valero Energy alongside its other brands Beacon, Shamrock, and Texaco (owned and used by Valero Energy solely in the United Kingdom and Ireland since its acquisition of its usage from Chevron in 2011).^[15]

The Diamond Shamrock brand is currently being used in Colorado, California, New Mexico, Oklahoma, Texas, and amongst other states.^{[citation needed]}