When people think of the largest companies in Silicon Valley, tech giants such as Apple (NASDAQ: AAPL), Google (NASDAQ: GOOGL) and Facebook (NASDAQ: FB) are the first that come to mind. However, successful public companies within Silicon Valley extend beyond the technology sector.

Wells Fargo & Co. (NYSE: WFC), Visa, Inc. (NYSE: V) and Chevron Corporation (NYSE: CVX), for example, are leading multinational firms that all have their headquarters in Silicon Valley.

1. Apple

Apple is one of the most successful companies in the entire world and is headquartered in Cupertino, California. The company has a current market cap of $650.8 billion and a price-earnings (P/E) ratio of 12.83 as of 2015.

Apple designs, manufactures and sells mobile devices, personal computers and digital music players, and it also sells numerous related software, services, networking solutions, and digital content and applications. The company's primary products include the iPhone, iPad, Mac, iTunes, operating system software and application software.

2. Google

Google is the most successful Internet search engine in the world and has a current market cap of $476.4 billion, giving the company a P/E ratio of 32.51 per share. The company has reached success on a massive scale since its inception and has business units that go beyond its search capabilities. It now offers a range of products and services across multiple screens and multiple device types. Google is headquartered in Mountain View, California.

Its products and services are offered in more than 50 countries in more than 100 languages. However, the company's biggest money maker is its offering of brand advertising and performance advertising. Google offers a self-serve platform for brand advertisers, agencies and publishers allowing them to power their digital marketing across display, mobile and video.

3. Facebook

Facebook is arguably the most world's most successful social networking company; it is based in Menlo Park, California. The company has a current market cap of $275.6 billion and a high P/E ratio of 99.57 per share.

Facebook was launched in 2004 by Mark Zuckerberg as a college social networking website, but it has since expanded to allow any person above the age of 13 to create a social profile. The company boasts billions of users and connects people through messages, status updates, photo and video sharing, and notification updates. The massive scale of the company has allowed it to offer highly targeted advertising, resulting in billions of dollars in annual revenue.

4. Wells Fargo

Wells Fargo breaks the mold of the recent rise of successful technology companies in Silicon Valley. The company was founded in 1852 and has grown to become the fourth-largest bank in the United States in terms of assets. It is the largest U.S. bank by market cap. The company has a current market cap of $270.8 billion and a current P/E ratio of 12.77 per share.

Wells Fargo, based in San Francisco, California, is technically a holding company that consists of three banking and financial services subsidiaries: community banking, wholesale banking, and wealth, brokerage and retirement.

5. Visa

Visa, like Wells Fargo, is another multinational financial services company based in Silicon Valley. The company has its headquarters in Foster City, California. Its current market cap is $171.77 billion, and its current P/E ratio is 21.53 per share.

The company specializes in the facilitation of electronic funds transfers through its credit card and debit card services. Visa doesn't actually issue cards or extend lines of credit; instead, it provides other financial institutions with payment products that they can offer to their customers.

6. Chevron

Chevron is a multinational energy company with its headquarters in San Ramon, California. The company has a current market cap of $169.27 and a current P/E ratio of 14.12 per share.

The company is technically an energy holding company made up of upstream and downstream segments. Combined, these segments combine to control the entire supply chain, from exploration, production and transportation to the refining and marketing of crude oil.

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