The ten biggest US tech companies will top $1 trillion in sales this year

• The 10 largest U.S. tech firms by revenue are expected to post aggregate sales of more than $1 trillion this year, an analysis of Wall Street estimates shows.
• The combined revenue of these giant companies is seen rising by $146 billion, or 15.7 percent, to $1.078 trillion in 2018, based on figures compiled by Thomson Reuters.
• Apple is the largest by sales but Facebook and Amazon will grow faster, analysts estimate.
• Apple and Microsoft, meanwhile, are both seen posting double-digit sales growth even after more than 40 years in business.

Tim Cook, chief executive officer of Apple Inc., waves after speaking during an event at the Steve Jobs Theater in Cupertino, California, U.S., on Tuesday, Sept. 12, 2017.

David Paul Morris | Bloomberg | Getty Images

In the technology sector, the biggest keep getting bigger — a lot bigger.

The 10 largest U.S. tech firms by revenue are expected to post aggregate sales of more than $1 trillion this year, possibly for the first time, an analysis of Wall Street estimates shows.

The combined revenue of these giant companies is seen rising by 15.7 percent, or $146 billion, to $1.078 trillion in 2018, based on the average estimates of stock analysts compiled by Thomson Reuters.

The figures show that the leaders of the tech industry are, on average, still growing at a robust pace even after eight consecutive years of U.S. economic growth.

The sector growth expectations also help explain why the 2017 performance of the Nasdaq 100 Index, representing the largest tech firms by market capitalization, outpaced the returns of both the broader Nasdaq Composite Index and .

The NDX rose 30 percent last year, while the Nasdaq Composite climbed 28.2 percent and the S&P 500, 19.4 percent.

Apple and Amazon are seen as sales leaders

Jeff Bezos

David Ryder | Getty Images

Apple is seen posting revenue of $273.3 billion for its fiscal year ending this September, as analysts bet that the new iPhone X will help it generate $44 billion in new sales.

Wall Street is expecting to hit $228.7 billion in sales this year, or $51.5 billion more than in 2017, helped by growth in its cloud computing business.

, and round out the top five tech firms by expected 2018 sales.

(The following figures are for either the current calendar year, or the companies' respective fiscal years ending in 2018.)

Largest tech firms by 2018 sales estimates:

Apple, $273.3 billion (FY ends in Sept.)

Amazon, $228.7 billion

Alphabet, $131.3 billion

Microsoft, $106.4 billion (FY ends in June)

IBM, $78.8 billion

Intel, $63.8 billion

Hewlett-Packard, $54 billion (FY ends in October)

Facebook, $53.8 billion

Cisco, $48.5 billion (FY ends in July)

Oracle, $39.8 billion (FY ends in May)

Facebook and Amazon growing fastest

revenue is expected to grow fastest this year among these tech giants, as more online marketers use its targeting technology for their digital ad campaigns.

Amazon is next, followed by Alphabet, Facebook's larger rival in the online ad market.

Apple and Microsoft, meanwhile, are both seen posting double-digit sales growth even after more than 40 years in business. Microsoft was founded in 1975 and Apple in 1976.

Projected 2018 sales growth:

Facebook, +34%

Amazon, +29%

Alphabet, +19%

Apple, +19%

Microsoft, +10%

, +5%

, +4%,

, +3%

, +1%

IBM, -0.4%