Despite recent warnings that the rally may be over, stock markets face a "meltup" as institutional investors will now feel obliged to buy to deliver returns, Philippe Gijsels, senior equity strategist at Fortis, told CNBC Monday.
A meltup is the opposite of meltdown, as investors feel forced to buy in the market so they wouldn't miss profit opportunities; but fundamentals don't justify this fervor, Gijsels said.
"Now you have the feeling of 'get me in at any price,'" as opposed to 'get me out at any price', he explained.
"You still have a lot of underbuying in the market," Gijsels told "Squawk Box" in London.
Institutional investors such as fund managers have only two months until the end of the year and they must show performance, he pointed out.