Global debt has hit another high, climbing to $247 trillion in the first quarter of 2018, according to a report published Wednesday. Of that figure, the non-financial sector accounted for $186 trillion.

The debt-to-gross domestic product (GDP) ratio has exceeded 318 percent, marking its first quarterly rise in two years, the report by the Institute of International Finance (IIF) said. This is amid record levels of corporate and household debt in many mature markets.

The unprecedented debt load is one of several investor concerns, in addition to worries about the Federal Reserve’s monetary policy tightening and the impacts of a trade war.

It's the debt in the corporate sector that market players should be worried about, said Joseph LaVorgna, chief Americas economist at Natixis.

“The corporate sector is highly leveraged and could be very vulnerable to higher interest rates,” he warned, explaining in a research note that a primary reason corporate debt-to-GDP is so high is thanks to interest rates being historically low due to quantitative easing and forward guidance.

“Firms have used artificially low rates to borrow in the capital markets and only buy back stock in the equity market,” LaVorgna said. “The inherent instability of debt over equity financing suggests that the next downturn could hit investment spending unusually hard.”