NEW YORK — Amazon’s Fire TV stick and a curved Samsung TV were top sellers during Amazon’s second annual “Prime Day” sales bonanza.

The e-commerce powerhouse launched the event last July to promote its $99 annual Prime loyalty program, which offers free two-day shipping and other perks.

Aside from a brief problem some customers had placing “Lightning Deals” into baskets Tuesday morning, no major hitches were reported.

ChannelAdvisor, which works with 3,000 retailers to sell products online including marketplaces like Amazon, said mid-day Tuesday that sales were in line with Prime Day 2015 in the U.S.

PiperJaffray analyst Gene Munster said ChannelAdvisor’s estimate might be conservative, however. He predicts Prime Day sales will grow 37 percent compared with the sale day a year ago because of more Prime members overall, better press coverage and stronger brand and merchant engagement with the date.

Amazon said the Fire TV stick, which was on sale for $15 off at $25, was the top seller of the day. Some other big discounts were on large screen TVs and Amazon devices such as its Echo smart speaker, Kindle e-reader and Fire TV-streaming device. Shoppers in the U.S. snapped up 22,000 TVs as of 11 a.m. E.T., Amazon said.

Shoppers had to be members of Amazon’s Prime loyalty program to get the discounts, but there is a 30-day free trial.

Other deals included $50 off Amazon’s Echo smart speaker on sale at $130, half off toys including Nerf and Barbie brands and up to 60 percent off athletic shoes. Most deals were on a limited-time basis, encouraging shoppers to check the site throughout the day.

In its study of about 2,000 products at 6 a.m. Tuesday, retail analytics firm Market Track said average discounts ranged from 20 percent to 30 percent, with the best deals on high-demand products including tablets, tools, video games, soundbars and toys.

Rick Ostopowicz, a marketing communications manager for a chemical company in Catonsville, Maryland, was disappointed in the deals last year during Prime Day. But this year he found deals on electronics: he bought bone conduction headphones that were $14 off at $35.99, a Wi-Fi range extender $50 off at $149 and a Wi-Fi router that was $30 off at $49.

“Pretty good savings so far,” he said, adding that he would have skipped the headphones without the Prime Day discount and Amazon’s generous return policy.

Some customers took to Twitter early Tuesday to complain about problems adding the “Lightning Deals” to their carts, but that problem was resolved by midmorning, Amazon spokeswoman Ana Rigby said.

Rivals countered Prime Day with deals of their own. Wal-Mart has cut prices throughout the month on a host of products online. Macy’s online site touted a “Black Friday in July” sale that runs through Sunday.

J.C. Penney and Toys R Us offered their own sales too.