Investors are often told that uncertainty is inevitable. No risk, no reward. Well, for those whose stomachs harden at the unknown, there's some good news. A growing number of tools prepare you for the threats lurking around the market, from a trade war to climate change, by letting you test them out on your investments before they ever happen. Many of these programs are only available to you through a financial advisor, though at least one company is discussing a way to develop an app that would be accessible to anyone. "Examining real-life scenarios allows you to understand ahead of time what type of potential downside and upside you have," said David Ristau, director of business development at HiddenLevers. HiddenLevers, based in Atlanta and used by some 3,000 advisors, has a library of unpleasant possibilities it can unleash on your portfolio. The pool is constantly updated. For example, a user can now see how a second government shutdown would rattle their investments.

Operations at HiddenLevers Source: Hidden Levers

Ristau provided some examples of commonly tested scenarios. A tech correction would bring a portfolio, with 80 percent stocks and 20 percent bonds, down around 20 percent. That same portfolio under a trade war with China? You're looking at a 30 percent haircut. As much as personal finance writers and experts repeat themselves about how the market recovers from its falls and that you lock in your losses when you sell at a discount, investors often still flee out of fear when they see red. "At the end of the day, we're human beings," said Vicki Bogan, an associate professor at Cornell University who researches investment decision making. "It's difficult to counterbalance the immediate loss of wealth, with, 'Oh well, in five years this will rebound.'"

Previously people were looking at risk based on history. It can be very forward looking now. Thomas Verbraken executive director of risk management at MSCI

Ristau hopes these programs will mentally brace investors for a market crash and reduce their chances of acting out of panic. "Think of it like talking to your family about what to do in an emergency," he said. "If you've gone over it several times, your family will act more calmly." Last year, BlackRock, the largest investment firm in the world, released its scenario tester. More than 50,000 financial advisors have already signed up to use the platform with their clients. "Advisors can say to their clients, 'You remember the financial crisis of 2008. How would your portfolio hold up today?'" said Ross Znavor, managing director of Aladdin wealth tech at Blackrock.

Of course, stress testing a portfolio is not new. After 2008, the government began to regularly examine how the country's major banks would respond to a variety of "what if" scenarios. But these tools have been more widely adopted in the last few years due to improvements in technology and the proliferation of data, said Thomas Verbraken, head of risk management solutions research at MSCI, a leading provider of investment decision tools and services. "Previously, people were looking at risk based on history," Verbraken said. "It can be very forward looking now. What would happen to my portfolio if there is a no-deal Brexit?" Yon Perullo, the CEO of Rixtrema, which already provides a scenario-testing platform to advisors, said they have considered creating an app in which anyone could see how their savings would respond to different problems.

Yon Perullo Source: Rixtrema

"I think people would want to know how certain scenarios would impact them in a retirement account," he said. These programs don't make precise predictions, Perullo cautioned. "You use these scenarios to understand your portfolio performance in different market environments," he said. "Not necessarily, 'This is going to happen'.' Cathy Curtis, a certified financial planner and founder/owner of Curtis Financial Planning in Oakland, California, uses the HiddenLevers scenario tester with her clients. "Sometimes I'll ask them, 'What's your biggest fear?'" she said.

Cathy Curtis Source: Cathy Curtis