Humana Inc. (HUM) shares tumbled 8.67% in pre-market trading on Wednesday, following the release of the company's second-quarter financial results and its decision to reaffirm rather than raise its full-year adjusted financial guidance.

The Louisville-based health insurer reported adjusted earnings per share of $7.61 for the second quarter, surpassing the consensus estimate of $7.22. However, the company maintained its full-year adjusted earnings outlook of at least $9 per share without revising its annual adjusted EPS or revenue range upward. The unchanged guidance appeared to fall short of elevated investor expectations, particularly as the company continues to face headwinds from lower Medicare Advantage star ratings that are expected to impact bonus revenue.

The pre-market sell-off suggests that while the quarterly results exceeded forecasts, market participants were looking for a more optimistic outlook amid ongoing concerns around cost trends and membership growth metrics. The reaffirmed guidance left investors uncertain about the pace of recovery in the company's key Medicare Advantage business, triggering the sharp decline in the stock.