SFBC ( SFCC) dropped 26% after postponing its earnings report and saying it expects to take a "substantial" impairment charge on its Miami clinical test business.

The Princeton, N.J., drug testing company said the charge is spurred by "the significant decline in business at our Miami operations." The company also vacated its 2006 guidance, provided Dec. 15, 2005.

The company said it will offer fourth-quarter results and its 2006 outlook after the market closes on March 8. SFBC had been set to offer 2005 numbers Thursday afternoon, but the company changed the schedule in a press release issued after 7 p.m. EST.

TheStreet.com reported earlier Thursday that short-sellers have been predicting a steep earnings hit linked to a decline in business at the lucrative Miami operation, and that investors have further questioned the company's accounting in a number of areas. The questions come as new top execs seek to revive the company in the wake of a Bloomberg report on the Miami unit that led to the ouster of the company's founder and other former leaders.

Early Friday, SFBC dropped $5.84 to $16.45.