Updated from 2:17 p.m. EDT

Shares of Luminex ( LMNX - Get Report) were among the worst-performing health and biotech stocks Thursday after the company reported weaker-than-expected second-quarter earnings and sales.

The biological testing company reported a loss of 4 cents a share on sales of $9.2 million. Analysts polled by Thomson First Call had expected it to report a smaller loss of 1 cent a share on sales of $9.4 million. Shares of Luminex traded down 72 cents, or 8.9%, to $7.33.

Sierra Health ( SIE) rose after it reported strong second-quarter financial results and raised its full-year earnings outlook. After excluding a one-time gain and factoring in convertible debt, the health insurer earned a better-than-expected 80 cents a share on sales of $441.2 million. Looking ahead, it now expects full-year earnings of $3.35 to $3.45 a share vs. its previous guidance of $2.90 to $3. Analysts were expecting $3.01 a share. Shares of Sierra Health traded up $1.13, or 2.6%, to $45.10.

Shares of AmerisourceBergen ( ABC - Get Report) rose after the company reported better-than-expected third-quarter earnings and sales. Excluding items, the drug wholesaler earned $1.02 a share on sales of $12.1 billion. Analysts had expected it to earn 98 cents a share on sales of $12.08 billion. Looking ahead, it now expects its full-year earnings to be in the middle of its previous guidance of $4.10 to $4.20 a share. It also raised its full-year cash-flow estimates to $650 million from $350 million to $400 million. Analysts are looking for the company to earn $4.15 a share for the full year. Shares of AmerisourceBergen traded up $2.29, or 4.4%, to $54.84.

Laboratory Corp. of America ( LH) rose after it posted better-than-expected second-quarter earnings and sales. The clinical lab services company earned 70 cents a share on sales of $784.3 million. Analysts had expected 66 cents a share on sales of $783.4 million. Looking ahead, the company now expects full-year earnings of $2.55 to $2.60 a share, higher than the $2.51 share analysts were expecting. Shares traded up $3.14, or 8.5%, to $39.94.

Shares of Align Technology ( ALGN) rose after the company reported better-than-expected second-quarter earnings results. Excluding one-time items, the maker of teeth-straightening products reported a profit of 9 cents a share on sales of $44.2 million. Analysts had expected it to earn 6 cents a share on sales of $43 million. Shares of Align Technology traded up $2.44, or 16%, to $17.70.

Other health care volume movers included Pfizer ( PFE - Get Report), up 51 cents to $32.51; Elan ( ELN), down $1.06 to $22; Boston Scientific ( BSX), down $2.08 to $33.27; ImClone Systems ( IMCL), up $1.24 to $64.76; Baxter International ( BAX), down $1.48 to $30.79; and Schering-Plough ( SGP), down 10 cents to $18.90.