 Shares of Labcorp LH, 0.76 tumbled 4.7 in premarket trading on Thursday after the diagnostics company said revenue in the third quarter of 2022 came in lower than expected as fewer people got PCR or antigen tests for COVID-19. Labcorp had earnings of 352.8 million, or 3.90 per share, in the third quarter of 2022, down from 587.3 million, or 6.05 per share, in the same quarter a year ago. 