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Last time this happened, stocks tanked

Mega-mergers are grabbing the headlines this week, but are they signaling a top in stocks?

According to data compiled by Thomson Reuters, roughly $1.5 trillion (that's with a "t") in merger transactions involving U.S.-based companies have been done since the start of 2014. That's the most since the tech bubble days of 2000.

And we all know what happened then.

With the S&P 500 now at all-time highs, some investors may be worried that a repeat of the market crashes of 2000 – or 2007 – may be in our sights. But one top trader says this time is different.

(Watch: S&P, Dow end at record highs as global worries ease)

"It's not a top," said David Seaburg, head of sales trading at Cowen and Company. "It's a very positive setup for a continuation of the secular bull market."

Unlike a decade ago, the recent crop of mergers and acquisitions has been mostly strategic, Seaburg said. "You don't have these venture firms … or private equity coming and taking companies at very high valuations."

He believes the driver for M&A activity has been a need for growth after companies cut their expenses as much as they could. Now they are using cheap money to buy more growth.

"Earnings growth over the past several years predicated on cost-cutting and stock buybacks," Seaburg said. "We're starting to see a turn…. Growth is on the horizon. CEOs are seeing it. They can't grow organically; it takes way too long. Strategic M&A is important in order to grow."

"It's going to continue to make this market and push it to trend higher," he added.

The charts on the S&P 500 also show why these days are different from 2000 and 2007, according to a leading technical analyst.

(Watch: Cashin: Why record highs are frustrating traders)

"It is a much more bullish setup now than it was then," said Ari Wald, head of technical analysis at Oppenheimer & Co., looking at an 85-year chart of the S&P 500. "We see this as a secular bull market. We've pushed above those 2000 and 2007 peaks."

Momentum is also on the side of a higher market when looking at a chart of the 10-year rate of change in the S&P 500 going back to 1936.

"Back in 2000, the 10-year rate of change was around 300 percent," Wald noted. "In 2007, it was at a lower level but it was still falling. Now we're still at a low level, but we're inflecting positively. This is a great setup here. This is much similar to the points in the 1950s and 1980s that led to these multiyear rallies."

Wald believes the markets will continue to make higher highs and higher lows. "U.S. stocks are the place to be," he said.

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