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NEW YORK (TheStreet) -- Sometimes selloffs can be bad, but most of the time they're opportunities to buy, buy, buy, Jim Cramer told his Mad Money viewers Tuesday. When the market gives you an opportunity, you should take it.

Cramer used this logic when considering buying United Technologies (UTX) for his charitable trust, Action Alerts PLUS, today. His thesis was that HVAC sales should be strong as the U.S. economy continues to heat up, something that was confirmed when HD Supply (HDS) reported earlier today. So when United Technology shares fell, he was ready to pounce.

Cramer admitted that perhaps his thesis is wrong, or he wasn't able to time the exact bottom in UTX, but that's why he invests for the longer term and buys positions in stages as stocks fall. He was too early recommending General Motors (GM) another Action Alerts PLUS holding, for example, and shares of Rite-Aid (RAD) still haven't settled since last week's recommendation. But that doesn't matter, Cramer said --  his theses for both these names remain intact.

When stores put merchandise on sale at the mall, people flock to it, Cramer noted, so when the markets put your favorite stocks on sale, investors need to be ready to pounce.

Off the Charts

In the "Off The Charts" segment, Cramer went head to head with colleague Bob Lang over the chart of Allstate (ALL), a stock that's quietly been moving higher and is now just off its 52-week high.

Looking at a daily chart of Allstate, Lang noticed the stock trading in a bullish channel, with higher highs and higher lows. The stock's volume has been confirming the move higher, and the Williams Oscillator, a measure of momentum, has been "embedded" in a long-term overbought condition for several weeks.

Allstate's weekly chart tells a similar bullish story, with the stock seeing a long march higher for the past two years, with both the relative strength indicator, RSI, and MACD momentum indicator both confirming the bullish trend.

On the fundamental side, Cramer said Allstate is still very inexpensive, trading at just 10 times earnings with an 8.5% growth rate. The company has been able to successfully combat rising costs with rising premiums and Allstate sports a solid 1.9% dividend as well.

The Urge to Merge

With the urge to merge running rampant on Wall Street, Cramer said it's worth while to talk about a merger that failed to happen -- the merger of equals between ad giants Omnicom Group (OMC) and the privately held Publicis.

Cramer said despite working on a deal since last summer, these two advertising Golaiths failed to come to terms and canceled their plans to merge. That may be bad news for Omnicom, he added, but it's great news for Interpublic Group (IPG), the number four player in the ad space.

Cramer explained that in the increasingly competitive advertising arena, Omnicom and Publicis were desperate to merge and increase their scale. So if they can't buy each other, why not buy Interpublic -- which is not only a cash cow but small enough to easily acquire.

Cramer reminded viewers that he never recommends a stock on a takeover basis alone. Interpublic also has terrific fundamentals. The company has instituted a successful turnaround, has a 1.9% yield and a $300 million stock buyback program. Shares trade at a scant 16.5 times earnings, but Cramer said it's likely worth 20 times earnings in a takeover scenario.

Executive Decision: Bob Carrigan

For his "Executive Decision" segment, Cramer sat down with Bob Carrigan, president and CEO of Dun & Bradstreet (DNB), the business credit information provider that's bought back over 58% of its own shares in recent years.

Carrigan said D&B's business is the same as its always been: providing companies with accurate and insightful credit information. But the way it gets that information and the modern ways it provides it have changed quite a bit over the years.

Carrigan noted D&B now has a database of 235 million companies around the globe and gets information from over 30,000 different sources. The database is updated over five million times a day, giving his company substantial advantages over all their competitors, he added.

Carrigan also said the delivery of its information has also changed, and D&B information can now be found natively inside modern applications like (CRM).

Cramer agreed, saying Dun & Bradstreet still has a bright future.

Lightning Round

In the Lightning Round, Cramer was bullish on Monsanto (MON), Concho Resources (CXO), Best Buy (BBY), Marathon Oil (MRO) and Stratasys (SSYS).

Cramer was bearish on Potash (POT), GameStop (GME), Chesapeake Energy (CHK), General Electric (GE) and 3D Systems (DDD).

No Huddle Offense

In his "No Huddle Offense" segment, Cramer opined on Chesapeake Energy's former CEO Aubrey McClendon and his announcement that his latest venture, American Energy Partners, is buying up $4.25 billion of oil and gas assets in Texas and West Virginia.

Cramer said that like him or hate him, McClendon is a visionary. If he's buying assets near companies like Pioneer Natural Resources (PXD), then perhaps Pioneer is worth a lot more than we realize.

To watch replays of Cramer's video segments, visit the Mad Money page on CNBC.

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-- Written by Scott Rutt in Washington, D.C.

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At the time of publication, Cramer's Action Alerts PLUS had a position in GE, GM, MRO and UTX.