The markets endured a brutal selloff, Jim Cramer told his Mad Money viewers Monday. But even with all of today's negativity, the worst may still be yet to come, Cramer cautioned.

There were several negative catalysts driving stocks lower, Cramer explained.

First, as the calendar turned over to December, many large funds began taking profits in their biggest winners. Many investors simply didn't see this profit-taking coming, Cramer said, which led to sellers overwhelming the few buyers that remained.

Then there's Roku (ROKU) - Get Report , the streaming device maker that always seemed to bounce back from negative news. That was until Monday's 15.1% decline.

The third negative in the markets was of course China, where hopes of the beginnings of a trade deal were dashed by a new U.S. resolution supporting Hong Kong. Cramer said rollbacks of existing tariffs are very unlikely with new tariffs just on the horizon. The Chinese may now be betting on next year's election, which will mean little progress in the short term.

Read: Trump Threatens 100% Tariffs on French Goods in Retaliation for Digital Tax

Finally, Cramer said there's Boeing (BA) - Get Report , which fell another 3% by the close as investors worry about the payments the aerospace giant may have to make to the airlines to make up for their 737-related losses. Cramer said with so many winners last month, investors were right to take some profits. But he cautioned that selloffs like this aren't over in a single session. It will likely take until Wednesday before all of the selling has subsided. 

Cramer and the AAP team are looking at everything from earnings and tariffs to the Federal Reserve. Find out what they're telling their investment club members and get in on the conversation with a free trial subscription to Action Alerts Plus.

The Stealth Winners

After a rough day for the averages, it pays to look at the market's biggest winners and ask if they can still go higher. In this market, that means looking at the stealth bull markets in JPMorgan Chase (JPM) - Get Report and UnitedHealth Group (UNH) - Get Report .

The big runs in both of these stocks had little to do with the economy, Cramer explained, and everything to do with politics. That's because some of the Democratic presidential candidates are advocating for universal healthcare, which could hurt companies like UnitedHealth. So when Elizabeth Warren surged in the polls, shares of UnitedHealth plunged, and when Warren's popularity waned, they rebounded.

The same holds true for JPMorgan, as candidates like Warren could seek to break up the biggest banks, or at least subject them to increased regulation.

With more moderate candidates gaining ground in the polls, Cramer said it's only natural that both UnitedHealth and JPMorgan are on the move. Both of these stocks are recession stocks, after all, and neither is held hostage to China.

On Real Money, Cramer keys in on the companies and CEOs he knows best. Get more of his insights with a free trial subscription to Real Money.

Off the Charts: VIX

In his "Off The Charts" segment, Cramer checked in with colleague Larry Williams for a fresh read on the direction of the markets. Williams' last prediction called for a selloff by year's end but he now thinks the tides have already turned and that selloff is coming early.

Williams looked at a daily chart of the CBOE Volatility Index to forecast that the fear gauge is heading higher, which means stocks will be turning lower. He predicted a market correction lasting until Feb. 11 before the bulls regain control.

Corroborating his thesis was the dollar index, which also foreshadows weakening in stocks, and the Commitment of Traders report, which shows the institutional money continuing to take profits. According to Williams, traders should sell into any strength, as there may only be one additional bounce before we head lower going into the new year.

Cramer said while he agrees that investors have become too complacent and stocks were due for a correction, he disagreed with Williams on the size and duration of the pending correction. Cramer said he thinks the move will be quicker and shallower than Williams forecasts.

Executive Decision: CyberArk

For his "Executive Decision" segment, Cramer spoke with Udi Mokady, cofounder, chairman and CEO of CyberArk Software (CYBR) - Get Report , the cybersecurity firm with shares up 60% for the year.

Mokady said that as more companies embrace the digital transformation, they need to protect themselves from hackers. Those hackers could be disgruntled employees or they could be hackers looking for ransoms, or even organized groups or nation states.

Protecting yourself is about a lot more than just having strong passwords, Mokady added, it's about monitoring your networks to ensure that passwords never make it into the wrong hands and responding properly to events if and when they do occur.

CyberArk's customers include everyone from the enterprise to government agencies, Mokady said, and certain sectors, like energy, have a lot of older, legacy systems that need to be upgraded and better protected from modern threats.

Executive Decision: eHealth

In his second "Executive Decision" segment, Cramer also sat down with Scott Flanders, CEO of eHealth (EHTH) - Get Report , the healthcare comparison website with shares up 136% in 2019.

Flanders started off by explaining that eHealth has been around for 12 years and helps people choose the best health plans for them. With over 60 million seniors, there are a lot of people who need guidance finding the right plan, especially for the millions of people who have never had to shop for a plan before.

Choosing the right plan for you is complicated, Flanders explained. That's why their agents are career consultants who must be licensed in every state and vetted by every health plan provider. Only one in 10 Americans is currently in the best plan, he added, and that's because there are so many variables like where you live, who your primary care provider is, which specialists you need to see and which medications you're taking, just to name a few.

When asked about the Medicare-for-all type plans being proposed by some Democratic presidential candidates, Flanders said with over 150 million people paying into employer-sponsored plans, he sees little chance people will vote for sweeping changes.

Lightning Round

In the Lightning Round, Cramer was bullish on Amgen (AMGN) - Get Report , Abiomed (ABMD) - Get Report , Northrop Grumman (NOC) - Get Report  and Lockheed Martin (LMT) - Get Report .

Cramer was bearish on Biogen Idec (BIIB) - Get Report , Caterpillar (CAT) - Get Report  and TEGNA (TGNA) - Get Report .

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At the time of publication, Cramer's Action Alerts PLUS had a position in JPM, UNH.