Donald Trump will be president and stocks will rally: O'Leary

Donald Trump CEO in Chief?

Donald Trump is bound for the White House, and when he reaches the Oval Office, stocks will "go straight up," said Kevin O'Leary, chairman of O'Leary Financial Group.

"I think what we're going to see happen — although it's so remarkable and I'm not endorsing his candidacy — is Trump is going to ride his way into the White House on a populist wave of anger at our government," O'Leary told CNBC's "Fast Money: Halftime Report" on Monday.

The "Shark Tank" investor, who claimed to be "agnostic to party," said state primary and caucus results have borne out what he has believed since the beginning of the election cycle.

"The old, crusty brands aren't going to work. Bush brand. Gone. Clinton's not going to work," he said.

Trump is heading into this week's Super Tuesday contests with a series of primary and caucus wins under his belt and a sizable lead in many states, according to various polls.

To be sure, some prominent executives and investors have openly worried about a Trump presidency.

After New Jersey Gov. Chris Christie endorsed Trump last week, Hewlett Packard Enterprises CEO Meg Whitman issued a statement Sunday saying: "Donald Trump is unfit to be president. He is a dishonest demagogue who plays to our worst fears. Trump would take America on a dangerous journey."

Whitman had been the financial co-chair of Christie's failed bid for the presidency.

Last month, Blackstone Group Chairman and CEO Stephen Schwarzman, a longtime Republican, told CNBC's "Squawk Box" that if he were faced with a choice between Trump and Texas Sen. Ted Cruz, he would "be really trying to figure out where we go."

Though he said he would opt for Trump in that scenario.

But O'Leary said he does not believe corporate America is truly afraid of a Trump presidency.

"He wants to solve the problems that we really have here in terms of straightening out the tax code, which I think is a big hold-back on these equity markets right now. It doesn't allow our companies to compete," he said.

The Tax Foundation concluded Trump's overall tax plan would "greatly increase the U.S. economy's size in the long run," but would also boost the government's deficit by $10 trillion over the course of 10 years.

As for Trump's more controversial social proposals, O'Leary said the real estate mogul's plan to build a wall between the United States and Mexico — and have Mexico pay for it — will never happen.

"He should say that, but when he actually gets the office, smoother heads around him actually have to manage this business around him," O'Leary said.

Republican U.S. presidential candidate and businessman Donald Trump listens as retired physician Ben Carson speaks during the debate in Milwaukee, Nov. 10, 2015.
GOP 'simple' flat tax proposals simply don't add up

O'Leary said it makes him sad to hear politicians beat up on the biotech sector or call the pharmaceutical industry untrustworthy.

Last year, Hillary Clinton said she would take on "price gouging" in the pharmaceutical industry. The comment sent shares of major biotechs on a downward slide.

If Clinton wins the presidency, investors will not be able to buy a biotech or health-care stock, O'Leary said.

"I have nothing against her. She's a fine woman. I respect her, but she has hurt me as an investor in biotech and pharma. These are great companies in America. They're doing the right thing," he said.

The pharmaceutical industry has come under criticism after a series of so-called tax inversions, or mergers carried out with the intention of obtaining a new tax domicile in a country with lower corporate tax rates.

The only reason pharmaceutical companies are doing inversions is because the U.S. tax code is "so screwed up," O'Leary said.

"Maybe Trump can come in and fix that, too," he said.

Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."