NEW YORK - The most valuable American companies at the start of the current bull market included an oil company, retail and consumer goods giants, and just one technology company.

The ranking seems very traditional, even a bit old-fashioned, compared to today, when big tech companies dominate the top of the market.

The top five most valuable companies at the end of February 2009 -- Exxon Mobil, Walmart, Microsoft, Procter & Gamble and AT&T -- include several in sectors that are generally considered safe, a reflection of investors' anxieties at a time the market was suffering huge losses.

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Today, the top four most valuable companies on the U.S. market are concentrated in technology. They've used innovations in commerce, communications and software to change how people spend their time and money, and how they work.

Apple's iPhone debuted in 2007 and was a fairly new product when the market hit its low point in early 2009. Today, it's the source of most of Apple's revenue. Thanks in part to steady sales and the iPhone' high profitability, Apple became the first public company valued at $1 trillion earlier this month.

Exxon, P&G, Walmart and AT&T remain among the most valuable companies on the market, but only one company that held a position in the top five in 2009 is still there today: Microsoft, which made huge gains in recent years by branching out into cloud computing.

Amazon, currently the second most valuable U.S. company at $925 billion in market capitalization, may have shaken up more industries than any other. Its focus on fast shipping and delivery to customers has forced companies that sell clothes, groceries, electronics and other goods to follow suit -- or risk falling out of favor with investors. Amazon was worth less than $30 billion back in March 2009.

Alphabet has made steady gains during the bull market as Google came to dominate the online search market and the advertising revenue that comes with it. Alphabet also runs several smaller tech businesses including Waymo, a self-driving-car company.

Warren Buffett's conglomerate Berkshire Hathaway is a bit of an anomaly at the top of today's market.

Berkshire does own a big chunk of Apple stock, but it isn't particularly focused on technology. It owns several insurance companies and has investments in railroads, airlines, banks and Coca-Cola. The firm's value has more than tripled during the bull market as investors rewarded it for deals including its purchase of Precision Castparts and Heinz Foods, which then combined with Kraft.