"Sell in May and go away."

It's a familiar phrase that was coined to describe a trader's decision to put money on the sidelines before heading to the Hamptons or Nantucket.

However, JPMorgan says that taking a vacation from stocks this summer will ultimately be a mistake for investors.

"We've had a couple of tough summers that are fresh in people's memory," said Stephen Parker on CNBC's "Futures Now" on Tuesday. "But, if you look back over the long term, history is not in your favor to sell in May and go away."

The head of thematic equity solutions for JPMorgan Private Bank believes that, even as the has risen 2 percent in the past month, more gains are to be expected. He noted that, since 1970, markets have actually rallied over the summer nearly 67 percent of the time.

However, while Parker warned that the period of time between Memorial Day and Labor Day tends to see more volatility, that can be in favor of bullish investors, since "we've had more 10 percent rallies over the summer than we have had declines."

Furthermore, Parker remains undeterred from the volatility that could stem from a Brexit. Regardless of how the U.K. votes on Thursday, he says that the market is ready because "de-risking" is already baked into investor's strategies.

"We're set up for a potential positive surprise heading into the rest of the summer," said Parker in his coverage. "History shows that market moves leading up to or immediately after some of these binary events often correct rather quickly."

And, if the Brexit turns out to be a nonevent in the market, positivity can be further spurred by a dovish Fed combined with high valuations.

"Valuations, we have to admit, are fully valued in terms of equity markets," added Parker. "So you're going to want to see earnings growth."

With this, Parker says that pressures from a stronger dollar and pressures from lower commodity prices have begun to subside. And, as markets move past the political headlines, he feels that the second half of the year is set up nicely for rallies in the U.S. and abroad.

"In Europe, you could potentially see a little bit of a catch-up trade," concluded Parker, who explained that fears around Brexit and uncertainty have seen European markets underperform U.S. markets in 2016. "The economic data out of Europe is improving. That's where we're looking for opportunities right now in markets."