At a conference this month put on by Turning Point Action, a rising conservative activist group, 8,000 people packed into a Detroit convention hall to hear directly from Republicans’ presumptive nominee for president, Donald J. Trump.

But first, there was a word from a sponsor: Alexander Spellane.

Mr. Spellane, who federal regulators say is also known as Alexander Fisher and Alexander Overlie, sells investments in precious metals. Cash, stocks and 401(k)s could plummet in value, he warned from the stage, but he told the throng of Trump supporters that they could protect their money by buying gold and silver from his company, Fisher Capital.

The Commodity Futures Trading Commission has been trying to shut down Fisher Capital’s sales for the past 14 months, alleging in a lawsuit that it sold gold and silver coins at such exorbitant, deceptive prices that virtually every customer had suffered “immediate and dramatic losses on their investment.” Fisher Capital has denied the allegations.

That lawsuit did not keep Turning Point Action from embracing Fisher Capital as a top-level sponsor of the Detroit event, which has required a donation of at least $250,000 and allowed Mr. Spellane to be photographed backstage with Mr. Trump. Mr. Spellane also claims to be the largest corporate sponsor of a sister group, Turning Point USA.

Mr. Spellane’s place on the Detroit stage offers a window into how Charlie Kirk, a young conservative activist and media personality who is close to both Mr. Trump and his son Donald Jr., has blended commerce and politics to transform a fringe initiative into a juggernaut with sweeping influence in right-wing circles. Turning Point Action, an advocacy group, and Turning Point USA, a charitable organization, were each created by Mr. Kirk and have each helped rally conservatives behind Mr. Trump.

This year, Turning Point Action says it plans to spend over $100 million to turn out voters in three battleground states.