By Liam Denning / Bloomberg Opinion

Elon Musk’s mix of wealth and celebrity, combined with his broad array of high-tech businesses around the world (and above it), makes him unlike other businesspeople who seek to curry favor with the White House. His prominent role in President Trump’s administration as de facto head of the Department of Government Efficiency has led some observers to refer to him as the “co-president.”

But the post-election Trump “bump” in Musk’s chief currency, shares in Tesla Inc., evaporated this week. Musk’s proximity to the president provided an initial boost to his fortune, taking it to almost $500 billion in mid-December, according to the Bloomberg Billionaires Index. The subsequent slump to $314 billion reflects, in part, the corrosive effect of that proximity on Tesla’s brand. Indications surfaced last week that Musk’s slash-and-burn approach to government efficiency is also angering some in Trump’s cabinet. Put together, these are the first hints of trouble in the defining relationship of our current politics.

Numerous business titans have floated in Trump’s orbit since his ascent to the presidency in 2017. Many have quickly fallen from favor. If Musk were to share that fate, the fact that he has tied his identity and corporate story so tightly to the president would make him and his business empire vulnerable.

Musk remains the richest person in the world despite Tesla’s 40 percent slide this year. But his stake in the electric vehicle maker, the only listed company in a stable that also includes Space Exploration Technologies Corp. and X Holdings Corp., is his most obvious source of personal liquidity. As of about a year ago, Musk had pledged 58 percent of his shares in the company as collateral for loans. When he was buying Twitter Inc., which became X, he sold tens of billions of dollars worth of Tesla shares. Having bounced somewhat off Monday’s low point, Tesla is still highly priced at almost 90 times forward earnings, compared with 21 times for the S&P 500 Index. Some analysts have begun cutting their estimates and price targets ahead of first-quarter results given big drops in vehicle sales in Europe and China.

Tesla’s stock is more than just a financial currency for Musk. It has become something like an opinion poll, a real-time verdict of sorts on Musk in his DOGE era; which can be summed up as euphoria devolving into disillusionment, with a whiff of panic. The recent selloff, in terms of 30-day change, eclipses even the crash in late 2022, when Musk was offloading shares during the Twitter acquisition, and is the steepest since the outbreak of the covid-19 pandemic. For investors, dreams of Trump helping to unleash a robotaxi revolution by easing regulations have collided with gathering evidence that Musk’s entry into government is damaging the EV maker’s brand when it needs all the help it can get.

This coincides with signs of strains within the White House. A New York Times report from inside a recent cabinet meeting surfaced tensions about Musk’s role. Several members, including Secretary of State Marco Rubio, pushed back on Musk’s sweeping job cuts — and snark, it seems — in front of both him and Trump. The president reportedly indicated his continued support for Musk but also clipped his wings, saying secretaries would be in charge of cuts in their respective departments, with DOGE merely advising. Soon afterward, Musk gave a TV interview in which he singled out entitlement spending as a key target for cuts, seemingly at odds with Trump’s promise not to touch Social Security and Medicare benefits.

Trump surrounded himself with a number of corporate titans at the start of his first term. Initially enamored with their status and business chops, the president eventually fell out with several of them, sparking high profile firings and resignations from an administration marked by incessant churn. Rex Tillerson, the former chief executive officer of Exxon Mobil Corp. — then among the 10 most valuable listed companies in the world — brought global experience and a certain Texas swagger to his role as secretary of state. He was gone in just more than a year amid reports of policy differences, battles with Trump’s son-in-law Jared Kushner and, most notably, an allegation that Tillerson had referred to the president as a “moron.” Gary Cohn, former chief operating officer of Goldman Sachs Group Inc., lasted about as long as director of the National Economic Council, affronted by Trump’s equivocal response to white supremacists’ violence at the 2017 Charlottesville rally and losing his internal battle against the use of tariffs.

It’s history like this, plus the personas of Musk and Trump, that has fueled speculation that this odd couple will ultimately split in a supernova of egos. For now, the things they offer each other remain largely intact. Musk retains both the ear of the president and influence, informal or otherwise, over agencies that regulate or contract with his companies. And Trump benefits from having a rich, prominent donor who controls a big social media platform and can act as a quasi-independent, and kinetic, force across the federal bureaucracy.

But Trump’s decision to turn the White House into a Tesla showroom last week in support of Musk served as a bizarre advertisement that all is not well. A healthy vehicle brand wouldn’t need the president to pledge to label protesters at its outlets domestic terrorists.

Recent polling finds a majority of Americans hold negative views of Musk and DOGE. And Musk’s string of recent setbacks coincide with troubling signs of a decline in Trump’s own popularity early in his term. His net approval rating, a positive 6.2 percent around his inauguration, has just flipped to a negative 0.7 percent, according to averages compiled by RealClearPolitics. The stock market, another measure Trump occasionally treats like a referendum, has convulsed in the face of erratic tariff policies, with the S&P 500 giving up all its post-election gains and then some. A new CNN poll found approval of Trump’s handling of the economy lower than at any time during his first term.

Musk’s tight, theatrical embrace of Trump — forgoing the red cap of MAGA for a black, “dark MAGA” version — appeals to the president’s prioritization of loyalty. It also makes Musk vulnerable if his dashboard indicators start blinking red, especially if the president feels pressured at the same time. Trump is mercurial. Should he face severe blowback over, say, entitlement cuts, or a big setback such as a recession, he might well decide Musk should take the fall on his behalf. After all, prior to allying last year, the two had some history of trading insults.

Who would have the edge in such a split? Trump might miss Musk’s money and followers and algorithmic alignment on X. On the other hand, the past decade has offered ample evidence of the durability of Trump’s own fanbase and he is ineligible to run for president again anyway. Moreover, Trump’s ability to turn the focus of federal regulators, plus his own followers, on Musk’s companies would be a deterrent to any counterpunch.

That Musk is now reportedly seeking to contribute another $100 million to Trump-aligned groups doesn’t just underline the cronyism of the White House Tesla event, it hints at a need to effectively renew his dues.

The recent plunge in Tesla’s stock owes partly to a backlash against the relationship with Trump. Paradoxically, therefore, recasting the president as a Tesla salesman this week will surely deepen that backlash. Having injected politics so deeply into the investment case of Tesla, and his other businesses, Musk must now live with the fact that what Trump gives, he can also take away.

Liam Denning is a Bloomberg Opinion columnist covering energy. A former banker, he edited the Wall Street Journal’s Heard on the Street column and wrote the Financial Times’s Lex column.