A blue chip is stock in a corporation with a national reputation for quality, reliability, and the ability to operate profitably in good and bad times.
The most popular index that follows United States blue chips is the Dow Jones Industrial Average, a price-weighted average of 30 blue-chip stocks that are generally the leaders in their industry.
All companies in the Dow Jones Industrial Average are blue-chips, but the Dow Jones Industrial Average is an index that does not include all companies that are blue chips.
As befits the sometimes high-risk nature of stock picking, the term "blue chip" derives from poker. The simplest sets of poker chips include white, red, and blue chips, with tradition dictating that the blues are highest in value.
In 19th-century United States, there was enough of a tradition of using blue chips for higher values that "blue chip" in noun and adjective senses signaling high-value chips and high-value property are attested since 1873 and 1894, respectively.