Apple (AAPL) stock has fallen roughly 18% from its record close in December, shedding more than $700 billion off the iPhone maker’s market cap as investors scrutinize the company’s AI play and evaluate macroeconomic headwinds.

Apple shares closed at an all-time high of $259 on Dec. 26 — just two weeks after the tech giant added ChatGPT to its iPhones as part of its second rollout of Apple Intelligence AI features — and the company’s market cap soared to a record $3.9 trillion.

Last week alone, Apple shares fell 11%, marking their biggest weekly loss since November 2022. And as of Tuesday midday, the iPhone maker’s market cap stood at roughly $3.2 trillion.

Apple shares have suffered in the first months of 2025 as Big Tech stocks have led a broader stock market downturn, driven by investor fears that the artificial intelligence boom could disappoint. Apple has also faced its own particular setbacks.

For one, Apple’s AI strategy is showing troubling cracks. On March 7, Apple delayed the release of an AI-upgraded Siri, saying the new Siri is taking longer than the company expected and should come out later this year. The move prompted Morgan Stanley analysts to lower their price target on the stock to $252 from $275 and cut iPhone sales forecasts. The analysts, led by Erik Woodring, expect Apple to ship 228 million iPhones in 2025 and 237.5 million in 2026, down from their prior estimates of 230 million and 255 million, respectively.

Woodring wrote in an analysis on March 12 that, according to Morgan Stanley’s consumer surveys, “‘an upgraded Siri personal assistant’ is the #1 AI feature prospective iPhone upgraders are interested in when upgrading.”

“Given our prior iPhone forecast assumed the iOS18.4 launch in April ’25 would integrate a more advanced Siri alongside broader Apple Intelligence language support and accelerate upgrade rates this fall, we believe it is necessary to lower our [iPhone] upgrade rate assumption, and FY26 shipment forecast, as a more advanced Siri is unlikely to be available until after the iPhone 17 launch,” he wrote.

“That’s not to say other factors cannot support iPhone growth in FY26 … but without a ‘killer AI app’ in market ahead of the iPhone 17 launch, we don’t see AI features contributing to accelerating upgrade rates as meaningfully as we did previously,” he added.

Adding to the heat on Apple, Trump’s tariffs on China threaten to add $2 billion to the company’s costs of goods and services over the next 12 months, according to a Morgan Stanley analysis last week.

Read more: What Trump’s tariffs mean for the economy and your wallet