It has been nearly 10 years since the worst of the financial crisis, and some investors may be wondering when the next big threat will materialize, especially since the U.S. stock market is in its longest bull market ever and currently trading at, or near, records.

According to Charles Schwab, there is both good news and bad news on this front. The good news is the global economy is better positioned, through regulation and technological advances, to protect itself against many of the kind of shocks that have historically risen to wreak havoc on share prices. The bad news is there are issues that could grow into crises at a time when the economy may be unusually vulnerable to one taking hold, and at a time when there are limited tools to combat such a scenario.

“The system is often at its most vulnerable near the end of the global economic cycle when excesses have built up and managing risks may have been neglected,” wrote Jeffrey Kleintop, Schwab’s chief global investment strategist, in research note dated Monday.

While Kleintop didn’t explicitly forecast a near-term crisis, he did express concern about global debt levels. This, he suggested could be both be the cause of a crisis, by resulting in a surge of inflation or higher interest rates, for example, or a factor that makes a crisis deeper and longer lasting by limiting the ability of institutions to combat an economic shock.

Citing data from the International Monetary Fund, Kleintop wrote that global debt stood at $164 trillion at the end of 2016, the most recent period for which data are available. That represents 225% of global GDP, and growth of $50 trillion from pre-financial-crisis levels……more here