Amazon sellers say the supply-chain crisis might limit their Prime Day stock. One said he still had $60,000 of products stuck on the Ever Given container ship.

• Amazon Prime Day kicked off on Monday, but some sellers say they are going in with stock shortages.
• One seller told CNBC he still had goods on the Ever Given ship, and would "severely limit" his Prime Day 2021 involvement.
• Experts say small traders could lose out because larger ones could afford to stock up in advance.

Amazon Prime Day is here - but some small businesses say they might struggle to keep up with consumer demand this year because of an ongoing supply-chain crisis.

Bernie Thompson, founder of electronics company Plugable Technologies, told CNBC that he had to "severely limit" his participation in Prime Day this year because of shipping-container shortages causing delays to imports.

A breakdown in the freight supply chain, caused by demand drying up in the first half of 2020 and coming back strongly at the end of the year, has led to port traffic jams and blockages. A lack of containers and dock workers has only made this worse.

Thompson also said that around $60,000 worth of his products were stuck on the Ever Given, a giant container ship that was wedged in the Suez Canal in March and has been impounded by the Egyptian authorities. Among these items are his USB docking stations, which were listed by Amazon as a top Prime Day deal in the UK in the past.

"We're about to run out of stock on that product on Amazon UK," he told CNBC. "There's no way for us to have a Prime Day deal in the UK. Our goods are on the Ever Given."

While some sellers had likely stocked up in advance, experts say smaller businesses might not have had the cash to buy in bulk, putting them at a disadvantage over Prime Day.

Others might have not had enough time to get orders in after Amazon bought its Prime day forward this year from July to June, giving sellers only three weeks' notice, Bloomberg wrote Monday.

Small businesses might also lose out to larger businesses when it comes to ad placement, experts said.

"If you're going to get certain advertising, they want to know what inventory is behind it," Rick Watson, CEO of RMW Commerce Consulting, which advises small businesses selling on Amazon, told CNBC. "It could advantage larger sellers this Prime Day, because it's more likely that they have the financial flexibility to make those commitments this year."

Watson said that all of his clients, who sell anything from furniture and homeware to clothing and food, are facing supply chain issues, but are still taking part in Prime Day.

Amazon did not immediately respond to Insider's request for comment.

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