The biggest technology companies and their chief executives donated millions to President Trump’s inauguration, hosted black-tie parties and dinners in his honor, and allowed him to announce and take credit for new multibillion-dollar manufacturing projects.

But less than three months into the president’s second term, Mr. Trump has hardly returned their lavish gestures with favors.

The sweeping tariffs he imposed last week will squeeze Apple’s iPhone supply chain and make it much more expensive for Amazon, Meta, Google and Microsoft to build supercomputers to power artificial intelligence. The president has slashed federal funding for research into emerging technologies like A.I. and quantum computing. His immigration clampdown has incited fears that he will cut off pipelines for tech talent.

The Trump administration has also signaled that it will continue an aggressive regulatory stance on reining in the power of the biggest tech companies, beginning next week with a landmark antitrust trial to break up Meta, the owner of Facebook, Instagram and WhatsApp.

Since the inauguration, the combined market value of Amazon, Apple, Google, Meta and Microsoft has fallen 22 percent to $10 trillion. And the tech-heavy Nasdaq index is down 21 percent.

The efforts to court Mr. Trump are a far stretch from the industry’s approach to his first administration, when many tech leaders were openly hostile toward the president. With an about-face and flattery, executives hoped this time around that Mr. Trump might show tech more deference, including it in his efforts to deregulate industries like energy and autos.