NEW YORK (Reuters) - Zale Corp (ZLC.N) shares fell 21 percent on Monday 7 December in their first trading session following the jewelry chain's disclosure that holiday sales had gotten off to a weak start.

Zale

Zale said in a regulatory filing late on Friday 4 December that sales at stores open at least a year, a measure known as same-store sales, fell 18.6 percent in November compared to the year earlier period.

Zale had not provided any holiday season forecasts when it reported earnings in November.

Zale, which operates 1,251 jewelry stores and 683 kiosks in North America, said in the filing that November has usually accounted for about 25 percent of revenue in the quarter.

The Dallas-based chain, which is being investigated by the U.S. Securities and Exchange Commission over the accounting practices that led it to restate its 2008 and 2009 earnings , gave no update on those proceedings. However, it said it did not believe the probe "will have a material effect" on its financial results.

The chain's shares were down $1.05, or 21.2 percent, at $3.91 on the New York Stock Exchange.

(Reporting by Phil Wahba, editing by Dave Zimmerman)