WASHINGTON - Regulators on both sides of the Atlantic are training their eyes on Apple, unnerving investors with fears over fines and threatening its market dominance.

In the United States, the Justice Department and 16 attorneys-general are suing the iPhone maker for violating antitrust laws. And in Europe, the company is said to be facing probes about whether it is complying with the region’s Digital Markets Act.

Shares of the company slid 4.1 per cent on March 21, erasing about US$113 billion (S$152 billion) in market value and taking their year-to-date loss back to 11 per cent. Once the world’s most valuable firm at more than US$3 trillion, Apple has underperformed both the Nasdaq 100 and the S&P 500 in 2024.

It is not the first time Apple is coming under regulatory scrutiny. The company and its peers have for years faced accusations of enriching themselves by suppressing competitors. But as Apple’s products have grown ever-more popular and established themselves as part of daily life around the world, the authorities have also become more combative and wary of its power.

The US suit, filed on March 21 in New Jersey federal court, accuses Apple of blocking rivals from accessing hardware and software features on its popular devices. The potential probes in Europe, which are also targeting some of Apple’s rivals, will focus on the firm’s new fees, terms and conditions for app store developers.

“There comes a point in which the downpour of cases and scrutiny that comes with them become a real drag on how these companies operate,” said antitrust professor Bill Kovacic from George Washington University Law School. “Even if they win, in an important way they’ve lost.”

Apple fired back at the US lawsuit by calling it “wrong on the facts and the law”. It warned that the action would “set a dangerous precedent, empowering government to take a heavy hand in designing people’s technology”, and vowed to “vigorously defend against it”. The company did not respond to a request for comment on the potential European probes.

The US lawsuit alleges that Apple has used its power over app distribution on the iPhone to thwart innovations that would have made it easier for consumers to switch phones. The company has refused to support cross-platform messaging apps, limited third-party digital wallets and non-Apple smartwatches, and blocked mobile cloud streaming services, according to the US Justice Department.

It highlights five examples of technologies in which it says Apple suppresses competition: super apps, cloud streaming game apps, messaging apps, smartwatches and digital wallets. The company recently added support for cloud-based gaming services and said it would add RCS cross-platform messaging later in 2024.

“At Apple, we innovate every day to make technology people love – designing products that work seamlessly together, protect people’s privacy and security, and create a magical experience for our users,” the company said in a statement. “This lawsuit threatens who we are and the principles that set Apple products apart in fiercely competitive markets.”

The Digital Markets Act (DMA) – which lays out a series of dos and don’ts for some of the world’s largest tech platforms – allows the European Commission to levy hefty penalties of as much as 10 per cent of a company’s total annual worldwide revenue, and up to 20 per cent for firms that repeatedly flout the rules. After starting formal investigations into Apple – as well as Alphabet’s Google – regulators aim to wrap up their final decisions within a period of 12 months.

Apple, fresh from its €1.8 billion (S$2.6 billion) European Union fine for blocking music streaming apps from informing users of cheaper deals, has been under heavy scrutiny since the DMA came into full effect on March 7. BLOOMBERG