The world’s equity markets have soared to new record highs, so naturally, investors are speculating about which company will become the next to achieve a $1 trillion market capitalization. Apple Inc. (NASDAQ:AAPL) is the natural frontrunner for this achievement, as its market cap approaches $600 billion again. But will it beat others to the punch?

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U.S. tech companies are top candidates

Writing on Investopedia, Elvis Picardo notes that so far, only one other company has achieved a market cap of $1 trillion. Late in 2007, China’s largest energy producer, PetroChina, Company Limited (ADR) (NYSE:PTR)’s market cap passed that level. It has since fallen off dramatically, however, and it sits around $230 billion.

When looking at the $500 billion market cap though, there have been six companies in the U.S. that have achieved that level. In addition to Apple, Cisco Systems, Inc. (NASDAQ:CSCO), ExxonMobil Corporation (NYSE:XOM), General Electric Company (NYSE:GE), Intel Corporation (NASDAQ:INTC), and Microsoft Corporation (NASDAQ:MSFT). In fact, at one time, Microsoft’s market cap surpassed Apple’s current market cap, soaring past $600 billion.

Apple faces off with Google

He notes that there are four big companies with massive market caps have: brand recognition, innovation, longevity and financial strength. He goes on to suggest that if someone conducted a survey of investors regarding which company they think will hit a $1 trillion market cap first, Apple would naturally be first, probably followed by Google Inc (NASDAQ:GOOGL) (NASDAQ:GOOG). Both companies are in the world’s top three most valuable companies, with Exxon Mobile ranking second on that list.

Picardo says what’s particularly interesting about Apple and Google is how quickly their market caps climbed. In the last ten years, Apple grew its market cap 43-fold or by $547 billion. That’s a 45% compound annual growth rate. In 2012, analysts slapped $1,000 price targets (prior to this year’s seven to one stock split) on Apple, suggesting about a $1 trillion market cap.

Meanwhile Google’s market cap has climbed nearly 11-fold in the same decade. In order for the search giant to hit $1 trillion though, it would have to grow by approximately 21% over the next five years or 10% a year over the next ten.

Tesla, SolarCity are dark horse contenders

Despite Apple and Google being obvious favorites for the $1 trillion market cap milestone, he also adds that it’s still possible for a dark horse candidate to come in and take it. For example, Facebook Inc (NASDAQ:FB) is the world’s 33rd biggest company after just two years as a public company. Amazon.com, Inc. (NASDAQ:AMZN) has a $150 billion market cap, which has skyrocketed by 580% in ten years. Other possible candidates he sees are Tencent Holdings Ltd (HKG:0700) and Gilead Sciences, Inc. (NASDAQ:GILD).

Other possible dark horses he names are Tesla Motors Inc (NASDAQ:TSLA), SolarCity Corp (NASDAQ:SCTY), and the currently private SpaceX, all companies Elon Musk is connected with.