The world's biggest companies by revenue represent relatively new, faster-growth industries and mature, slower-growth ones ranging from ecommerce and tech devices to oil and retailing. No matter what, each company is a dominant force in its industry. While each of these companies has seen its business shift as a result of the COVID-19 pandemic, some companies continue to thrive due to their unique advantages as millions of consumers shelter in place.

These are the 10 biggest companies in the world by 12-month trailing (TTM) revenue, and it represents a striking diversity of industries.This list is limited to companies that are publicly traded in the U.S. or Canada, either directly or through ADRs. Some foreign companies may report semiannually, and so may have longer lag times. We add the caveat that two other companies that otherwise would be added to this list are Saudi Aramco, the Saudi state oil company; and State Grid, the Chinese state-owned electric utility. They were omitted because their stocks are not publicly traded in the U.S. or Canada. All data in this story are provided by YCharts and as of Sept. 10, 2020.

Some of the stocks below are only traded over-the-counter (OTC) in the U.S., not on exchanges. Trading OTC stocks often carries higher trading costs than trading stocks on exchanges. This can lower or even outweigh potential returns.

#1 Walmart Inc. (WMT)

  • Revenue (TTM): $542.0 billion
  • Net Income (TTM): $17.9 billion
  • Market Cap: $392.8 billion
  • 1-Year Trailing Total Return: 22.4%
  • Exchange: New York Stock Exchange

Founded in 1962, Walmart has since grown into one of the world's largest retailers. The company operates discount stores, supercenters, neighborhood markets, as well as a robust online platform. Walmart sells a wide variety of merchandise including clothing and apparel, home goods, books, jewelry, food and beverage, pharmaceutical supplies, and automotive equipment.

#2 China Petroleum & Chemical Corp. (SNP)

  • Revenue (TTM): $355.8 billion
  • Net Income (TTM): $486.6 million
  • Market Cap: $53.5 billion
  • 1-Year Trailing Total Return: -21.7%
  • Exchange: New York Stock Exchange

China Petroleum & Chemical is a producer and distributor of a variety of petrochemical and petroleum products. The company's products include gasoline, diesel, kerosene, synthetic rubbers and resins, jet fuel, and chemical fertilizers, among other related offerings. Also known as Sinopec, China Petroleum & Chemical is among the largest oil refining, gas, and petrochemical companies in the world. It is administered by the State Council of the People's Republic of China.

#3 Amazon.com Inc. (AMZN)

  • Revenue (TTM): $321.8 billion
  • Net Income (TTM): $13.2 billion
  • Market Cap: $1.6 trillion
  • 1-Year Trailing Total Return: 78.5%
  • Exchange: NASDAQ

Amazon is the world's largest online retailer by market cap. The company began as an online bookseller and has since grown to encompass virtually every category of retail. Besides selling products through its ecommerce platform, Amazon owns subsidiaries including Whole Foods Market and home security company Ring. Amazon's fastest-growing areas of business are cloud computing services, subscription products like Amazon Prime, and streaming movies and other entertainment.

#4 PetroChina Co. Ltd. (PTR)

  • Revenue (TTM): $320.0 billion
  • Net Income (TTM): -$1.8 billion
  • Market Cap: $59.2 billion
  • 1-Year Trailing Total Return: -34.8%
  • Exchange: New York Stock Exchange

Oil and gas company PetroChina is engaged in oil exploration, development, production, and sales. It also manufactures petrochemical products. PetroChina is the exchange-listed branch of the Chinese state-owned China National Petroleum Corporation.

#5 Apple Inc. (AAPL)

  • Revenue (TTM): $273.9 billion
  • Net Income (TTM): $58.4 billion
  • Market Cap: $2.0 trillion
  • 1-Year Trailing Total Return: 121.3%
  • Exchange: NASDAQ

Apple designs, manufactures, and markets a broad range of consumer technology products, including smartphones, personal computers, tablets, wearable devices, home entertainment devices, and more. Among the company's most popular products are its iPhone line of smartphones and Mac line of computers. Apple also is building a fast-growing services business, operating digital content stores, selling streaming video games, and providing streaming services such as Apple+, a platform for on-demand entertainment content.

#6 CVS Health Corp. (CVS)

  • Revenue (TTM): $264.0 billion
  • Net Income (TTM): $8.3 billion
  • Market Cap: $77.2 billion
  • 1-Year Trailing Total Return: -3.6%
  • Exchange: New York Stock Exchange

CVS is an integrated pharmacy health care provider. The company operates a chain of drugstores with locations throughout the U.S. as well as in Puerto Rico. Aside from retail, CVS offers pharmacy benefit management services, mail order pharmacy services, and disease management programs.

#7 Royal Dutch Shell PLC (RDS.A)

  • Revenue (TTM): $263.1 billion
  • Net Income (TTM): -$11.3 billion
  • Market Cap: $110.1 billion
  • 1-Year Trailing Total Return: -46.5%
  • Exchange: New York Stock Exchange

Based in the Netherlands, Royal Dutch Shell explores, produces, and refines petroleum through its subsidiary companies. In addition to operating gas stations around the world, Shell produces and sells fuels, lubricants, and other chemicals.

#8 Berkshire Hathaway Inc. (BRK.A)

  • Revenue (TTM): $260.5 billion
  • Net Income (TTM): $22.2 billion
  • Market Cap: $520.9 billion
  • 1-Year Trailing Total Return: 6.5%
  • Exchange: New York Stock Exchange

Berkshire Hathaway is a diversified holding corporation that owns companies in broad range of sectors and industries. The include insurance, energy generation, freight rail transportation, retail, and manufacturing companies, among others. The company also holds a substantial portfolio of equity securities and derivatives.

#9 Toyota Motor Corp. (TM)

  • Revenue (TTM): $248.6 billion
  • Net Income (TTM): $14.4 billion
  • Market Cap: $182.7 billion
  • 1-Year Trailing Total Return: 1.8%
  • Exchange: New York Stock Exchange

Toyota is a Japanese automobile company that manufactures, sells, leases, and repairs passenger cars, trucks, and buses worldwide. The company also sells parts and equipment and operates financing services. Aside from its core business, Toyota also develops intelligent transportation systems utilizing cruise control and electronic toll systems and builds pleasure boats and homes as well.

#10 Volkswagen AG (VWAGY)

  • Revenue (TTM): $247.4 billion
  • Net Income (TTM): $6.4 billion
  • Market Cap: $94.8 billion
  • 1-Year Trailing Total Return: 11.2%
  • Exchange: OTC

Volkswagen Group is the world's largest automobile manufacturer by vehicle sales. The German company builds, sells, and repairs both luxury and economy cars, sports cars, trucks, and other commercial vehicles. VW's premier luxury brand is Audi.