Markets watchers are buzzing off Tuesday's all-time peak for the tying the record for the longest bull run in history.

But investors shouldn't get carried away, some strategists warned Wednesday as soaring equities are currently unique to the U.S., amid a backdrop of waning returns everywhere else.

This is the position of Ian Harnett, chief investment strategist at London-based Absolute Strategy, discussing what that historic intraday high will mean for market sentiment.

"I don't think it makes any difference at all — I think we're looking at actually the great American bull market," Harnett told telling CNBC's "Squawk Box Europe." "Because if you look outside America, this bull market has already rolled over."

Harnett pointed to a pullback in global equities since the start of the year. Indeed, global equities are down 1 percent, and European equities in dollar terms are down 7.7 percent, with emerging markets down another 7.9 percent. Asia's benchmark MSCI Asia Pacific index has slid about 6 percent since the year's start.

The U.S., by contrast, is up 6.2 percent.

"So, actually, this is fake news — this bull market is fake news because there's a rolling correction that is overtaking markets, currency markets and equity markets, and you're seeing symptoms of this throughout the market space," Harnett said.

Even in sectors where bull market investors normally invest, returns aren't so happy, the strategist said. Mining equities in Europe are down 15 percent in the last three months, for example, and European banks have fallen 30 percent in dollar terms from their late January peak.

"That is a disaster if you've been a high beta, strongly convicted bull in these markets," Harnett said.