) -- It's witching day in the market, and the retail sector is not immune from the day's mythical volatility.

The S&P Retail Index was up 1% to 386.05 and shares of companies within the sector saw some big movements.

Witching day happens once each quarter and is the day on when four contracts expire: stock-index futures, stock-index options, stock options and single-stock futures. Such multi-expirations are known to cause volatility.

One of the biggest retail gainers is sports-apparel store


(ZUMZ) - Get Report

, which soared 10.5% to $16.96. The specialty retailer was upgraded to neutral from underperform by an analyst at Wedbush Morgan.

"We believe Zumiez benefited from solid back-to-school selling during the Labor Day weekend, and while there may be some deceleration in the latter half of the month, we believe September sales will once again demonstrate an improvement from year-to-date trends," analyst Betty Chen wrote in a client note.



also climbed 4% to $68.50 after it announced it has

launched its own third-party market place


Wal-Mart Stores

(WMT) - Get Report

also rolled out this feature earlier in the month.


(GME) - Get Report

leveled up 2.5% to $26.48 in afternoon trading, as noise grows that video game sales could shape up during the holidays.

Rumors have been circulating that


Wii could even see a price cut, following price cuts for


(SNE) - Get Report

PlayStation and


(MSFT) - Get Report

Xbox 360.

Rite Aid

(RAD) - Get Report

gave up some of its gains this week, falling 1% to $2.21. The drugstore rallied 32% this week.



declined 2% to $7.15 and

Office Depot

(ODP) - Get Report

dropped 5.5% to $6.03.

-- Reported by Jeanine Poggi in New York

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