Earnings Surprise Drives Diagnostic Stocks Surge, Adding Over 2 Trillion Won in a Day

Quest Diagnostics Inc. (NYSE: DGX) jumped 6.65% on April 21, closing at $209.36 and lifting its market capitalization by roughly $1.6 billion (about ₩2 trillion) in a single day to approximately $23 billion (around ₩30 trillion). Trading volume surged to 1.39 million shares, reflecting concentrated buying interest driven by its recent results and growth story.

In its first quarter of fiscal 2026, Quest Diagnostics reported revenue of about $2.89 billion, up more than 9% year over year and ahead of analyst expectations. Organic revenue and test volumes both posted double-digit gains, prompting the company to raise its full-year 2026 revenue and earnings outlook.

Headquartered in Secaucus, New Jersey, Quest Diagnostics is the largest independent diagnostic testing provider in the U.S., offering hospitals, healthcare professionals and employers a wide range of diagnostic services—including blood tests, minimal residual disease cancer testing and drug screening.

Having increased its dividend for 15 consecutive years, the company recently raised its quarterly dividend by 7.5% and expanded its share-repurchase authorization by $1 billion, further cementing its reputation as a defensive dividend-growth stock backed by stable cash generation.