Updated from 3:03 p.m. EDT

Shares of

Patterson

(PDCO) - Get Report

were among the worst-performing health-related stocks Thursday, falling 14.2% after the company posted fourth-quarter results that fell short of Wall Street expectations and said that first-quarter earnings would be lower than expected.

The supplier of dental products posted earnings of $50.2 million, or 36 cents a share, on sales of $627.3 million. Analysts surveyed by Thomson First Call were expecting earnings of 39 cents a share on sales of $631.3 million. A year ago, the company earned $45.1 million, or 33 cents a share, on sales of $537.4 million. Patterson said fourth-quarter earnings were below planned levels and blamed the shortfall on a combination of business factors, including a LIFO provision that was higher than expected and additional expenses related to certain field-personnel incentive programs.

Looking ahead, Patterson forecast first-quarter earnings of 31 cents to 33 cents a share. Analysts had been expecting earnings of 34 cents a share. For the full year, the company forecast earnings of $1.54 to $1.58 a share, below the $1.60 a share that analysts had been expecting. Shares traded down $7.50 to $45.46.

PSS World Medical

( PSSI) rose 8.3% after the company posted fourth-quarter earnings that were in-line with expectations on sales that were better than expected. The distributor of specialty pharmaceutical products earned $10.2 million, or 16 cents a share, on sales of $401.3 million. Analysts were expecting earnings of 16 cents a share on sales of $395.5 million. A year ago, the company earned $6.6 million, or 10 cents a share, on sales of $351.4 million. Looking ahead, the company said it is positioned for continued above-market growth in earnings and sales. The company expects to grow earnings by 20% for fiscal years 2006 through 2008. Shares traded up 94 cents to $12.34.

Shares of

Immunomedics

(IMMU) - Get Report

fell 10.8% after the company said it received a notice of delisting from

Nasdaq

officials. Immunomedics said Nasdaq notified the company that a private placement executed in April did not comply with Nasdaq rules. "Specifically, the staff advised that it believes that the antidilution protections for the holders contained in the notes and warrants could potentially reduce the conversion price of the notes and exercise price of the warrants to a price below market value on the date of issue and therefore violate the rule," the company said in a regulatory filing. As a result, Nasdaq officials are reviewing the company's eligibility for continued listing on the exchange.

Immunomedics said it is working to resolve the issues. The company said it has agreed to not issue any shares of stock that would trigger the antidilution provisions identified by the Nasdaq letter. What's more, the company intends to explore the possibility of amending the terms of the notes and warrants, though there is no assurance that any such effort would be successful, it said. Finally, Immunomedics plans to file an application with the

American Stock Exchange

to transfer the listing of its stock to Amex. The company plans to talk with Nasdaq to find out if a dual listing is possible. Shares traded down 23 cents to $1.90.

Other health care volume movers included

Elan

(ELN)

, up 84 cents $8.05;

Able Laboratories

( ABRX), up 63 cents to $4.87;

Pfizer

(PFE) - Get Report

, up 23 cents to $28.90;

Eyetech Pharmaceuticals

( EYET), down 69 cents to $13.94;

Boston Scientific

(BSX) - Get Report

, down $1.30 to $28.16;

Merck

(MRK) - Get Report

, down 19 cents to $32.35;

Amgen

(AMGN) - Get Report

, up 32 cents to $62.70;

Schering-Plough

( SGP), up 5 cents to $19.79;

Johnson & Johnson

(JNJ) - Get Report

, down 5 cents to $67.42; and

Aastrom Biosciences

(ASTM)

, down 10 cents to $2.62.