The Standard & Poor's 500, the largest global equity market, broke 2,000 for the first time on Monday.
The S&P rose .7 percent to 2,001.95, partly due to firmer equity markets seen in the European Central Bank. It is also a result of several corporate deals including Burger King's acquisition of the Canadian coffee and doughnut chain Tim Horton's.
Business heads and market watchers are cautious about their optimism on the milestone.
"It's just a number and we need to see the economy, earnings and revenues expand and justify the achievement of the S&P rising above 2,000 points," Jack Ablin, chief investment officer at Harris Private Bank, told the Financial Times.
JJ Kinahan, chief strategist at TD Ameritrade, said that if the S&P maintains its numbers it may be a sign of a sustainability bullish market.