Not all retailers had a fruitful Cyber 5 sales weekend. Some were plagued with website and mobile issues that drove shoppers to other retailers or to voice their complaints on social media.

Costco Wholesale Corp., No. 15 in the 2019 Digital Commerce 360 Top 1000, encountered a number of problems, including shoppers who were unable to complete their purchases. 

Costco.com was down completely for a brief time early morning Thanksgiving and experienced intermittent slow load and transaction times beginning late Wednesday evening, according to site monitoring company Catchpoint. Their issues ended around 7:15 p.m. ET Friday, but Catchpoint noticed intermittent issues for a short time Saturday afternoon as well. 

During the issues, a banner on its site read: “The website is currently experiencing longer than normal response times. Please note that all Thanksgiving Day-only promotions have been extended into Friday, November 29th, WHILE SUPPLIES LAST. We apologize for any inconvenience.”

All together, Costco’s downtime—which Catchpoint defines as an inability to complete a transaction—totaled 17 hours.

Those issues caused the retailer to lose about 40% of its Thanksgiving Day online sales, mobile optimization company Yottaa estimates, as shoppers who encountered problems likely went to other retailers’ sites to make their purchases, says Bob Buffone, chief technology officer at Yottaa. For example, one shopper noted on Twitter that after attempting to buy an iPad Pro on Costco.com, she ended up buying it on Amazon.

Costco did not respond to a request for comment regarding its website issues.

The website issues caused a huge loss for the company, says Mario Ciabarra, CEO of digital analytics platform Quantum Metric. He estimates the retailer may have lost up to $11 million in revenue, as well as caused a huge rift in customer relationships.

“During Cyber week, the stakes are high, and these glitches are good reminders for any retailer to instill a more proactive mindset when developing and designing their websites and applications, as the reality is many often struggle to fix issues like these until days later,” Ciabarra says.

Apparel merchant H&M (No. 29) also was down for a short time—fewer than five minutes—on Thanksgiving Day, but went down again on Friday morning, according to Catchpoint. Not only that, but H&M’s app also had issues on Black Friday, Digital Commerce 360 found. Altogether, HM.com’s downtime totaled 10 hours, Catchpoint says. H&M did not respond to a request for comment.

Some other online retailers experiencing technical issues, such as slow load times or consumers being unable to complete their transactions, on Thanksgiving and Black Friday included Lululemon.com (No. 82) and JCrew.com (No. 62), according to Yottaa. These retailers also experienced technical issues during the Cyber 5 period last year.

For example, Lululemon in 2018 faced a barrage of angry comments on Facebook late Thanksgiving evening, in which shoppers complained about the site being down or items disappearing from their shopping carts. It responded to multiple complaints and wrote, “Our team is working with all their might on sorting out this issue.”

J. Crew had issues during last year’s Black Friday, when it experienced “some technical difficulties” on JCrew.com as buyers flocked to its site for 50% off everything deals.

The biggest factor in year-over-year site outages during the Cyber 5 is inadequate website load testing, says Yottaa’s Buffone. “They often times simply do not have the internal resources to make sure their sites won’t crash during peak periods, such as the Cyber 5,” he says. “If they don’t make changes to their load testing methodologies and they don’t move to a hosted platform, they will probably be on the list of sites that crash during the Cyber 5 next year.”

Lululemon and J. Crew did not respond to a request for comments on their technical difficulties this year. 

These website issues could hurt retailers’ bottom lines, says Moody analyst Mike Zuccaro. “Retailers need to be on top of being able to invest in the right systems and have a seamless shopping experience, especially with the highest volume sales days of the year on the line,” he says.

As of 2 p.m. ET on Cyber Monday, Catchpoint found that all retail sites it tracks were running smoothly.

Analytics platform Blue Triangle, however, found that Saks Fifth Avenue (owned by Hudson’s Bay Co., No. 41) was experiencing site issues on Cyber Monday and, as a result, extended its sale through Tuesday. 

On the flip side, some retailers were working at peak performance during the Cyber 5 period. The top three fastest-loading ecommerce sites were Amazon.com (0.7 seconds), VictoriasSecret.com (1.5 seconds) and Apple.com (1.7 seconds), according to Catchpoint. And the top three fastest-loading mobile sites were Amazon.com (0.6 seconds), eBay.com (1.4 seconds) and Apple.com (1.5 seconds). Measurements taken are median web page load times for the time period of all-day Thanksgiving through 3:30 a.m. ET Dec. 2, Catchpoint says.

On average, Digital Commerce 360 Top 500 websites slowed 38% between Thanksgiving Day through Cyber Monday, Blue Triangle finds. This is likely due to the increase in traffic compared with the Thursday-Monday period the week prior: it increased 105% Thanksgiving Day, according to Blue Triangle. On the following days, traffic increased 43% from Thanksgiving Day to Black Friday and rose 66% from Sunday, Dec. 1, to Cyber Monday. However, traffic dropped 40% from Black Friday to Saturday and decreased 20% from Saturday to Sunday.

Overall, compared with the Thursday-Monday period prior to the Cyber 5 period, traffic to retail sites increased 61%, Blue Triangle says.