UnitedHealth is putting pressure on the 30-stock index Thursday after the insurance giant reported a rare revenue miss. This is what you need to know.

UNH stock is finally returning to form after UnitedHealthcare CEO Brian Johnson was gunned down outside an investor meeting in Midtown Manhattan on December 4, leading to a weeklong manhunt that brought light to UnitedHealth’s record of denying health claims and general unpopularity with the public.

UNH has a split post-earnings history over the last two years, finishing four next-day sessions higher and four lower. The stock also averaged a 4.6% swing, regardless of direction, after its last eight earnings reports. This time around, the options pits are pricing in a bigger 6.9% move.

Shares of UnitedHealth Group ( UNH -4.86%) were pulling back Thursday after the company delivered underwhelming fourth-quarter results, as sales were weaker than expected and its costs rose. As of 1:15 p.