The Northern Trust Open, formerly known as the Nissan Open and originally known as the Los Angeles Open, is a regular golf tournament on the PGA Tour. It is played annually in February in Pacific Palisades, California. The tournament has been contested at the Riviera Country Club on a near-continuous basis since 1973. Chicago based Northern Trust Corporation, a leading provider of investment management, asset and fund administration, fiduciary and banking solutions for corporations, institutions and affluent individuals worldwide is the current sponsor of the event.

In 2005, the tournament was shortened by 36 holes due to rain. Adam Scott defeated Chad Campbell on the first hole of a sudden-death playoff on a Monday. Due to the event's length, this win is counted as unofficial for Scott.

In September 2007, it was originally announced that Bearing Point, a McLean, Virginia based consulting firm, would become the new title sponsor of the tournament.

However, on October 15, 2007, Northern Trust, one of the nation's largest personal trust companies and a leading provider of wealth management services, became the title sponsor of the PGA Tour's tournament at Riviera Country Club in Los Angeles, beginning in February 2008.

The five-year agreement, which extends through the 2012 event, was announced October 15, 2007, by PGA Tour Commissioner Tim Finchem and William A. Osborn, Chairman and CEO of Northern Trust Corporation. The tournament will be known as the Northern Trust Open, and the new partnership marks the beginning of a process of transformation for this high-profile tournament.

As part of the initial move to enhance the tournament, the Northern Trust Open will increase its purse to $6.2 million in 2008, an increase of $1 million over this year. Additionally, the tournament pro-am will go from four amateurs to three per group. Further changes and upgrades are planned and will be announced at a later date.