Shopify experienced instability for hours on one of the busiest shopping days of the year. Last year, it handled $11.5 billion between Black Friday and Cyber Monday.

• Shopify experienced an outage on Cyber Monday, disrupting merchant transactions.
• The outage mainly affected business login and point-of-sale systems.
• Shopify powers over 10% of US e-commerce, and its stock fell 5.8% on Monday.

It was a tough day for one of the nation's largest transaction platforms to experience instability.

Shopify suffered an outage on Cyber Monday, freezing some merchants out of their accounts and point-of-sale systems during one of the busiest shopping days of the year.

The financial impact is still unclear. A spokesperson directed Business Insider to the company's status page.

Many small business owners posted on social media to tell shoppers that their shipping labels could not be generated and that they may experience issues during checkout.

Outage tracker Downdetector showed a spike of roughly 4,000 problem reports at 11 a.m. ET, with thousands more pouring in around 1:15 p.m. ET.

The Canadian e-commerce transaction giant said early afternoon on its status page that some sellers were "experiencing issues" with Shopify admin, Point of Sales, Mobile, and Shopify Support.

By mid-afternoon, Shopify reported that services were recovering after engineers fixed an issue with the company's login authentication flow, though pockets of disruption remained.

"We are seeing signs of recovery for admin and POS login issues now," Shopify said in a 2:31 p.m. ET update, adding that teams were still monitoring the situation.

By 3:38 p.m. ET, Shopify said in its most recent status update that its Help Center is still "experiencing longer than normal wait times."

As of 9 p.m. ET, Point of Sale, API & Mobile, and Support are still considered to have "degraded performance."

Shopify powers more than 10% of US e-commerce sales. The company's President, Harley Finkelstein, said in a press release on Saturday that the platform processed $6.2 billion in gross merchandise volume on Black Friday, up 25% year over year, led by cosmetics, activewear, fitness, and nutrition.

Shopify's stock closed 5.8% down on Monday.