The S&P 500 has gained more than 10% since December's selloff and the market has been bullish in its future outlook, especially since it has been resilient despite the ongoing government shutdown.

However, many analysts argue that current highs are artificially bolstered, and that the market is just oversold. In fact, the Global Economic Policy Uncertainty Index has just reached an all-time high of 304, which is "more than three times the historical median reading of 101," writes Goldman Sachs analyst David Kostin.

The Global Economic Policy Uncertainty Index is compiled using data gleaned from newspaper articles. Newspaper articles tend to inflate the degree to which the market is bearish or bullish in order to make content more readable and therefore may not be the most reliable method of gauging market conditions.

Still, the number is alarming when combined with other figures. Equity-risk premiums are very high right now, which indicates that uncertainty levels are also high because the risk-reward ratio is skewed and investors expect more. Right now, risk-free 10-year Treasury premiums are at 3.6%, which is above the average of 2.3%.

"Despite positive signals around recent negotiations, stocks exposed to U.S.-China trade show persistent uncertainty," said Kostin. "Baskets of U.S. stocks with high China sales exposure and China stocks with high US sales exposure...remain depressed relative to levels early in 2018 before the escalation of tensions," he continued.

There is more of a valuation cushion today than there was last year in that 2019 estimates multiples are high, or at about 15.5.

Of course, the shutdown hasn't been priced in. The shutdown is especially risky since were there to be a true economic downturn, policymakers may not be able to react in an effective or fast enough manner. Ed Keon, chief investment strategist at QMA said: "In the U.S. there's been a lot of churn at the top level. If you do have a slowdown in the economy, how do you deal with it, and who's going to craft the response?"