Reaction Records was an independent British label, founded Robert Stigwood in 1966. That year, Stigwood became The Who's booking agent, and he also became manager of newly formed band Cream, comprised of musicians from two groups that he already had under contract: guitarist Eric Clapton from John Mayall's Bluesbreakers, and Jack Bruce and Ginger Baker from The Graham Bond Organisation.
These developments led to the formation of Reaction Records, and all three albums on the label were by these two bands, two by Cream and one album by The Who. Shortly after, The Who's management started their own record label, Track Records, and Reaction was absorbed by Polydor in late 1967. The label was distributed by Polydor.
Robert Stigwood moved on to start RSO Records in 1974.