Shoppers looking for bargains on http://www.target.com/ were greeted with an error message: "So sorry, but high traffic's causing delays. If you wouldn't mind holding, we'll refresh automatically & get things going ASAP."

Target representatives did not immediately respond to a request for comment.

In what Target has called its "Biggest, Boldest Plans" for Cyber Monday, the retailer is offering 15 percent discounts on almost all items on Target.com.

Deals include 50 percent off licensed kids' cameras including Frozen and Teenage Mutant Ninja Turtles and select Sennheiser in-ear headphones.

Upscale retailer Neiman Marcus's website was unavailable most of Friday, according to website performance monitor Catchpoint Systems.

Other websites that have faced outages since early Thursday include L Brands Inc's Victoria Secret and Foot Locker Inc, according to Catchpoint.

About 121 million shoppers planned to shop online on Cyber Monday, down slightly from the 126.9 million who planned to participate last year, according to the National Retail Federation.

Target's shares were down 1.2 percent at $72.52 in morning trading.