Updated from 11:41 a.m.

Shares of

Gander Mountain

( GMTN) were among the

Nasdaq's

losers Friday, falling 16.5% after the company trimmed guidance.

The outdoor specialty retailer now expects pretax income of $2 million to $4 million, down from previous guidance of $8 million to $13 million. Sales are now expected to be between $640 million and $645 million. Previously, the company expected sales of $640 million to $670 million. The company also expects same-store sales to decline 2% to 3%. Previously, Gander had forecast a decline of 1% to 3%.

Gander Mountain said that unseasonably warm weather forced discounting and hurt margins.

The latest warning marks the second time in 10 weeks that Gander has reduced full-year guidance. On Nov. 9, Gander Mountain shed 25% of its value after it warned Wall Street that full-year results would be significantly below previous guidance. At the time, investors were expecting pretax income of $16 million to $21 million, sales of $675 million to $700 million and comp-store sales growth of 3% to 5%.

Shares of Gander have fallen by more than 40% since going public in April. Shares traded down $1.86 to $9.43.

Tesoro

(TSO)

fell 2.5% after the company warned that fourth-quarter earnings would fall short of expectations. The independent refiner expects to earn 5 cents to 10 cents a share, which includes an after-tax charge of 10 cents a share. Analysts had been expecting earnings of 42 cents a share. Results were hurt by operational problems at its Hawaii refinery and weaker margins in December. Shares traded down 76 cents to $29.55.

Shares of

Kennametal

(KMT) - Get Report

rose 3.5% after the Latrobe, Pa., toolmaker raised its second-quarter earnings outlook. The company now expects earnings of 74 cents a share on sales of $550 million. Previously, the company had forecast earnings of 60 cents to 65 cents a share. Analysts had been expecting earnings of 66 cents a share on sales of $525.7 million. Broad end-market strength and gains in market share led to the revised outlook. Full results will be issued on Jan. 26. Shares traded up $1.65 to $48.80.

Bowater

( BOW) fell 2% after the newsprint company warned that fourth-quarter results would fall below expectations. Excluding items, the Greenville, S.C., company expects to post a loss of 45 cents to 55 cents a share. Analysts had been expecting a loss of 13 cents a share. Weak fourth-quarter market pulp and lumber prices contributed to the weaker outlook. Shares traded down 81 cents to $39.49.

Shares of

National Penn Bancshares

(NPBC)

fell 3.5% after the company postponed its 2004 financial results. The company had expected to report earnings on Jan. 20. However, on Jan. 6 and 7 the company "discovered evidence suggesting irregularities in certain loan and deposit account that appear to be the result of intentional misconduct. At present, such misconduct appears to be limited to the acts of a single person," the company said. "At this time National Penn has not determined the financial impact of these irregularities and, if any losses did occur, whether they will be covered by insurance or loan loss reserves, or will be recoverable in a civil action."

National Penn said it is working to complete the investigation in a timely manner. Shares traded down 92 cents to $25.26.

NYSE

volume leaders included

Lucent

( LU), up 8 cents to $3.51;

Nortel

( NT), down 7 cents to $3.33;

Pfizer

(PFE) - Get Report

, down 8 cents to $25.25;

Advanced Micro Devices

(AMD) - Get Report

, unchanged at $15.16; and

General Electric

(GE) - Get Report

, up 29 cents to $35.52.

Nasdaq volume leaders included

Sun Microsystems

(SUNW) - Get Report

, down 36 cents to $4.22;

Microsoft

(MSFT) - Get Report

, down 15 cents to $26.12;

Intel

(INTC) - Get Report

, up 20 cents to $23.02;

Cisco

(CSCO) - Get Report

, up 10 cents to $18.88;

Applied Materials

(AMAT) - Get Report

, up 28 cents to $16.53;

Sirius Satellite Radio

(SIRI) - Get Report

, down 1 cent to $6.45;

Oracle

(ORCL) - Get Report

, up 15 cents to $13.63;

Cree

(CREE) - Get Report

, down $9.19 to $25.88;

Taser International

(TASR)

, down $1.16 to $19.64; and

Apple Computer

(AAPL) - Get Report

, up 40 cents to $70.20.