$Amazon.Com Inc(AMZN.US)$ is expected to report strong profits Thursday after its midyear Prime Day event boosted sales, and its cloud computing and advertising units continued to grow.

The Seattle-based e-commerce giant's success in the pandemic comes as U.S. consumers increasingly meet their shopping, entertainment and work needs online, strengthening the power of the world's largest technology companies.

Using its size and leverage, Amazon this year has looked to increase its foothold in non-retail industries, even as federal regulators continue to circle the company and scrutinize its growth and business plans.

Amazon is set to post second-quarter earnings after markets close Thursday. Analysts polled by FactSet on average predict $115.4 billion in quarterly revenue and per-share earnings of $12.28. The company in April said it expected second-quarter sales to be between $110 billion and $116 billion and operating income between $4.5 billion and $8 billion.

The retailer has been exceeding financial expectations since the start of the pandemic, which brought a flood of shoppers and new growth to the company's e-commerce operations that it has been able to sustain. Still, analysts predict Amazon's tremendous growth will slow down, as the economy reopens from the height of the pandemic, when it saw earnings nearly double.

"That's something we expect to happen because of the extraordinary circumstances of last year," said Ron Josey, an analyst with JMP Securities. "As long as top line growth is there, I think (results) will be well-received."

Amazon's second-quarter earnings will be aided by its annual Prime Day shopping event, which the company this year moved up from its typical third-quarter date.

The April-to-June stretch marked Amazon's last quarter under Jeff Bezos, the company's founder, who left the chief executive role on July 5 to become executive chairman. Andy Jassy -- an Amazon lifer who headed its cloud-computing unit, Amazon Web Services -- is expected to bring an ultra-detail-oriented management style to the company's top position, The Wall Street Journal reported earlier this month.

Amazon's results Thursday come after a strong showing by other large tech companies this week. Microsoft Corp. on Tuesday reported record quarterly revenue, as its Azure cloud-computing segment saw year-over-year sales growth of 51%. Fueled by strong iPhone sales, Apple Inc. posted its biggest spring-quarter profit, while Google parent Alphabet Inc. reported its highest quarter ever for sales, as businesses continued to rely heavily on its advertising services.

Demand for computing power has long bolstered Amazon's earnings. Such needs have grown during the pandemic, as more companies look to boost server capacity and software tools. Amazon Web Services, which offers such tools, generates a significant portion of Amazon's operating income. Its sales, which had been slowing in recent quarters, picked back up to start the year.

Amazon has also become a dominant force in advertising behind Google and Facebook Inc. The ad unit has been expanding at a high double-digit clip.

Amazon's trillion dollar valuation hasn't stopped it from trying to add businesses to its empire, even as its power has received more scrutiny from policy makers. Amazon in May announced it had agreed to acquire the Hollywood studio MGM in a deal valued at $8.45 billion. The acquisition is being reviewed by the Federal Trade Commission.

The FTC also has an open, wide-ranging antitrust investigation into Amazon's business practices. In addition, Amazon is also battling a broad set of bills in Congress aimed at reining in the market dominance of big tech companies. One bill, named the "Ending Platform Monopolies Act," could make it easier for federal regulators to break up the companies, lawmakers have said. Amazon has defended its competitive practices in part by arguing that it operates products and services to benefit customers.

Aside from regulatory concerns, Mr. Jassy faces internal challenges as Amazon's new CEO. The company last week said it launched an investigation at Amazon Web Services after an employee petition, which garnered hundreds of signatures, alleged that the cloud unit systematically discriminated against women and minority groups. The Washington Post first reported on the investigation and petition.

In an email to the petitioner's authors reviewed by the Journal, AWS Chief Executive Adam Selipsky said Amazon had hired an outside investigation firm and that he would review its findings.

Labor unions also continue to put pressure on the retailer, which has the second-largest U.S. workforce. Earlier this year, Amazon employees at a warehouse in Bessemer, Ala., voted not to unionize. The International Brotherhood of Teamsters, one of America's largest labor unions, passed a resolution in June designed to aid Amazon workers in eventually achieving a union contract in part by creating a special division to organize workers there. Amazon has said that a union is unnecessary because its workers already receive competitive pay and benefits.

Write to Sebastian Herrera at Sebastian.Herrera@wsj.com