President Donald Trump, the virtual elephant on the stock-market floor, claimed credit for its rise since his election in November 2016.
And as he has denounced trade deals, threatened trade wars and attacked Amazon, he has put himself at the center of the downturn as well.
Yahoo Finance launched a new video feature recently entitled, "This Week in Trumponomics."
Last week, the S&P 500 index of America's largest companies fell 9 percent from its January highs. More than half the 69 publicly traded Minnesota stocks worth more than $2 per share are trading in negative territory this year.
Some analysts believe stocks should be higher after December's corporate tax cuts and a good 2018 earnings outlook.
However, after Trump's trade threats last week, the market tanked.
That's even after Trump's new economic adviser, Larry Kudlow, suggested the president's pronouncement may just be a negotiating ploy.
Trump's outbursts and sometimes-contradictory statements, from immigration reform to troop deployments and global trade, have succeeded in at least one thing: increased volatility in the stock market.