Super Micro said in its business update on Tuesday that some delayed customer platform decisions in the third quarter have moved sales into Q4.
In addition, the company said it expected net sales to come in at $4.5bn (£3.4bn) to $4.6bn, down from previous guidance of $5bn to $6bn.
Meanwhile, earnings per share was expected to be between $0.16 and $0.17, down from a prior forecast of $0.36 to $0.53.
Jim Reid, market strategist at Deutsche Bank, said: "This is a company that was a darling of the AI world and peaked out at around 118 early in 2024 and will likely open in the low 30s today."
This comes as Starbucks CEO Brian Niccol seeks to turn the company around, which included speeding up service and cutting back its menu to focus on core coffee products.
Niccol acknowledged the downbeat results, saying "our Q2 results are disappointing," but added that "behind the scenes we made a lot of progress and have real momentum with our 'Back to Starbucks' plan."
"My optimism has turned into confidence that our back to Starbucks plan is the right strategy to turn the business around and to unlock opportunities ahead," he said.
Another stock falling sharply in pre-market trading on Wednesday was social media platform Snap (SNAP), which tumbled nearly 14% after hours.
On Tuesday, Snap posted first quarter revenue of $1.36bn, which was about in line with expectations, as was the daily active users number of 460 million.
On the UK market, shares in pharmaceuticals firm GSK (GSK.L) were up more than 4% on the back of its first quarter results.
GSK posted first quarter sales of £7.5bn ($10bn), which were up 4%, while earnings per share increased by 56% to 39.7p.
The company continued to expect turnover growth of 3% to 5% in 2025 and core operating growth of 6% to 8%, as well as core earnings per share growth of 6% to 8%.
Sheena Berry, healthcare analyst at Quilter Cheviot, said that GSK "delivered a solid quarter of growth".
"As with its peers, however, investors are arguably most interested right now in the impact any potential tariff regime may have on the company," she said. "GSK has sought to reassure the market that is can withstand any pressure that tariffs may bring, and is in fact well positioned to respond. The group has identified mitigation options in the supply chain and productivity initiatives should sector specific tariffs be implemented.
"That said, what does eventually get implemented, if anything, is a guessing game and the full impact will not be known at this stage, but it is pleasing to see GSK take the potential risk seriously and look for options to weather the storm."
On the FTSE 250 (^FTMC), shares in Aston Martin (AML.L) were up 1.7% on Wednesday morning, after the struggling luxury carmaker delivering first quarter results that were in line with guidance.
Aston Martin posted first quarter revenue of £233.9m, which was down 13% from the same period last year, though losses before tax shrunk to £79.6m from £138.8m in Q1 2024.
Adrian Hallmark, CEO of Aston Martin, said that the company was "carefully monitoring the evolving US tariff situation and are currently limiting imports to the US while leveraging the stock held by our US dealers. We remain vigilant in monitoring events and will respond to changes in the operating environment as they materialise."
Despite global economic uncertainty, Aston Martin kept its 2025 guidance unchanged and said it expected to make "significant improvements across all key financial performance metrics" this year.
Aarin Chiekrie, equity analyst at Hargreaves Lansdown, said: "Aston Martin continues to burn through cash on its road to redemption, and there are big hopes that the release of its Valhalla supercar in the second half can drive a return to profitability. Liquidity is a key metric to watch. There’s currently around £400m available, with the previously announced Yew Tree investment and sale of its stake in its Formula One team set to bring in a further £125m of funds.
"But as things stand, Aston Martin’s burning through its cash resources, with losses widening in the first quarter," he added. "The net debt pile’s growing too, with much of this carrying double-digit interest rates, meaning the group’s fighting an uphill battle."
Other companies in the news on Wednesday 30 April:
