On the surface, it may appear that Donald Trump’s presidency is a boon for business. The stock market certainly seems to think so: The Dow Jones industrial average almost reached 20,000 this week in anticipation of lower taxes and deregulation.

But Trump’s rhetoric and questionable behavior actually undermine confidence in the United States as the world’s premier place to do business.

The president-elect’s conflicts of interest, refusal to release tax info, reliance on family to unofficially conduct government business, Twitter broadsides against individual companies and general unpredictability will hurt the U.S. economy long after he leaves the White House. Such habits will bring us closer to the way China, Trump’s favorite foil, and his bestie Russia operate, and reduce our ability to press other countries to clean up their business practices.

“It does not appear that the law can provide controls on the conflicts of interest created by a Trump presidency,” said Philip Nichols, professor of legal studies and business ethics at the University of Pennsylvania’s Wharton School. Some businesses may try to ally their interests with those of the Trump operations, he said, but “decisions made on the basis of self-interest work against the interest of business in general, particularly over the long run.”

Trump’s seeming indifference to conflicts of interests and the appearance of clean government could leave the impression that his administration is open to selling Uncle Sam. Foreign nations have reportedly even booked rooms at Trump’s hotel in Washington, hoping to curry favor with the new president.

That is not to say that Trump is corrupt. But we’ve never had a president with such extensive global business ties. Appearances do matter, which is why we need to embrace the best practices of good governance now more than ever.

“To a varying degree, corruption afflicts economies at all stages of development,” according to a report by the International Monetary Fund. “Indeed, certain advanced economies score worse on perceptions of corruption than some developing countries.”

And it’s a slippery slope from conflicts of interest to corruption.

The United States is the best place in the world for business because the country is home to places like Wall Street and Silicon Valley, where capital and liquidity intersect with talent and innovation. But the rule of law is what holds these things together. It inspires confidence among investors and entrepreneurs that people and companies operate under the same sets of rules.

The United States is, of course, not perfect. But there’s a reason the country, despite the turmoil of the dot-com bubble and housing crisis, remains the largest and most dynamic economy in the world. There’s a reason investors around the world continue to buy and hold U.S. debt.

Among outside, independent groups, the United States consistently gets top marks for both business environment and rule of law. To create a strong economy, the two go hand in hand.

The World Bank ranks America eighth in the world for ease in starting a business, noting the country’s strengths in obtaining credit and resolving insolvency. (New Zealand, Singapore and Denmark are among those that ranked higher.) European officials have told me that they especially admire U.S. bankruptcy laws, which allow companies and entrepreneurs second chances.

At the same time, the World Justice Project gives the United States high scores in areas like lack of corruption, regulatory enforcement, open government, and order and security.

By contrast, the World Bank ranks China, the world’s second largest economy, 78th in starting a business, behind nations like Bhutan, Azerbaijan and Botswana. China is also rife with corruption. During my trips to Beijing and Shanghai, academics, journalists and even government officials said that corruption, along with pollution and poverty, are the country’s top problems.

If you have the right connections to government, a company could do quite well in centralized, authoritative nations like Russia and China, said Thomas Joo, a professor of law at UC Davis who specializes in corporate governance and contract law.

“Everybody hates favoritism,” Joo said. “Unless they are the favorites.”

But corruption ultimately saps an economy’s strength, creating market distortions that ultimately stunt growth.

The World Economic Forum estimates that the cost of corruption amounts to $2.6 trillion a year, 5 percent of the world’s economic output. Private-sector corruption in developing countries alone amounts to at least $500 billion, more than three times the amount of foreign assistance given in 2012, according to a report by the Center for Strategic & International Studies think tank in Washington.

Corruption impacts all countries, rich or poor.

“Markets work best when they are fair and competitive, and safety nets and socially oriented programs work best when they are impartial,” Nichols said. “Crony capitalism destroyed the banking system in South Korea, gutted economic growth in Indonesia, and has contributed to grossly distorted systems in any number of emerging economies.”

“Do business firms really want to operate in a system where they are pressured to make deals on the basis of who the other party knows rather than the soundness of the deal?” Nichols said.

That’s what makes Trump’s behavior and rhetoric so troublesome.

He has failed to offer a plan on how to effectively remove himself and his family members from the Trump Organization, his main company, once he takes office. Indeed, his daughter Ivanka Trump and son-in-law Jared Kushner appear to closely advise Trump on government matters. Ivanka Trump even attended a recent meeting with Japanese officials. Trump has tweeted that he plans to turn over his business to two of his older children (not Ivanka, who will follow him to Washington). But he’ll always know his buildings, and that his kids are running them.

Trump will accelerate what’s already happening in the U.S. — a decline in the rule of law, said Robert Amsterdam, a partner with Amsterdam & Partners law firm in Washington and London, who advises companies on international law. Since 2001, the country has undermined the rule of law and civil liberties with the Patriot Act, the prison at Guantanamo Bay, and CIA rendition and torture of terrorism suspects.

The dot-com bubble and the Great Recession, the worst economic downturn since the Depression, also severely undermined confidence in the Securities and Exchange Commission and the Office of the Comptroller, the very regulatory agencies designed to protect investors and consumers, Amsterdam said.

Trump takes all of this to a new level.

For example, Trump has already shown he can affect the market values of companies by tweeting negative things about them. He could easily hurt business rivals with a single 140-character broadside — as he is already doing for political enemies.

What makes Trump’s presidency particularly troublesome is that we’re currently operating in a sustained era of low global economic growth. The temptation to create jobs at the expense of good governance might be too great.

Trump has boasted that he can boost U.S. gross domestic product growth to over 4 percent. To this end, he has already stacked his incoming administration with CEOs and business leaders. But these are the very people who will be leading the agencies charged with regulating the markets and protecting people.

In fact, Trump’s ascendance reminds me of an unwritten but unmistakable deal between China and its citizens. The people are willing to tolerate a one-party state as long as the government keeps the economy growing and creates jobs.

But at what cost to the country?

Thomas Lee is a San Francisco Chronicle columnist. Email: tlee@sfchronicle.com Twitter: @ByTomLee