Tesla ( TSLA 4.77%) shares have tumbled 20% this year, while the S&P 500 (SNPINDEX: ^GSPC) has jumped 5%. Poor financial results driven by market share losses are the main source of consternation, but CEO Elon Musk has arguably damaged the brand with his behavior.

Wall Street faces uncertainty as Tesla shares drop after Elon Musk announces a new political party. Discover the impact.

Last week, the Trump administration announced that it reached a deal with Vietnam that would allow U.S. goods to enter the country duty-free, while Vietnamese exports to the U.S. would face a 20% levy. That was a decline from the 46% tax on Vietnamese imports he proposed in April.

World shares are mostly higher, with financial markets shrugging off U.S. tariff pressures on its trading partners

Wall Street ended mixed a day after a broad sell-off in response to the Trump administration setting new tariffs on more than a dozen nations.

Mr. Musk’s involvement in politics and his financial support for the president’s campaign were once seen by investors as a benefit to Tesla, fueling a steep rise in company shares after the election last year. That association has now turned into a liability. Tesla shares are down 40 percent from their peak in December.

One analyst called on Tesla's board of directors to act and set "ground rules" for Musk's political involvements.