If 2018 was a record-breaking year for CEO optimism worldwide, as per PwC’s annual global survey of chief executives, this year’s outlook stands in sharp contrast.

Since last year, the share of CEOs who expect global economic growth to decline increased 436%, according to the survey (conducted in September and October 2018), which tracks responses from around 1,400 CEOs across more than 90 regions. Optimism among North American CEOs dropped the most, from 63% in 2018 to 37% this year.

The number of leaders who expect global economic growth to improve in 2019 (42%) continues to outnumber those who say it will decline (29%), but by a smaller margin than in 2018. Last year, 57% believed the global economy was on the uptick – a percentage higher than any other year since 2012. Meanwhile, a mere 5% believed it was poised to decline.

What’s more, when considering their own organizations’ growth prospects, 35% of CEOs indicated feeling “very confident” about their company’s future over the next 12 months (compared to 42% last year). The percentage that expressed optimism for their businesses over a three-year window, meanwhile, dropped nine percentage points to 36%.

According to PwC, the threats business leaders consider most pressing “are less existential and more related to the ease of doing business in the markets where they operate.” For example, the top concerns were “over regulation” and “policy uncertainty” (at 35% each), followed by “availability of key skills” (34%).

PwC attributes the shakier-than-normal outlook to international trade tensions, political instability and uncertainty, as well as stricter monetary and fiscal policy. These forces may “all play out differently but with the same general result across regions: a more cautious outlook on global economic growth.”

In addition to unveiling the results of its survey, PwC returned to the answers of previous studies in order to “analyse the predictive power of CEOs.”

As it turns out, chief executives have proven themselves to be rather prescient. Historically, there has been a “strong correlation” between CEOs’ expectations for their own organisations’ revenue growth and actual global GDP growth the following year. “In other words,” note the report’s authors, “CEOs’ revenue confidence can be considered a leading indicator of the direction of the global economy.”