Et tu, Phil? The FBI and the SEC are investigating good-guy golfer Phil Mickelson for possibly violating insider-trading laws. Say it ain’t so!

Phil Mickelson: not the happiest of times.

Aside from golf fans and convicted insider-trading felons like Martha Stewart, the story may be of interest to companies that shell out big bucks to sponsor top athletes. As a Sunday article in Bleacher Report pointed out, Mickelson is at risk of losing deals with his sponsors, including KPMG, Barclays, Exxon Mobil and Amgen, that provided the bulk of his $45 million off-course earnings for 2013.

None of them is giving Phil a show of support, or making any comment at all. But as Bleacher Report’s Michael Fitzpatrick suggested, they probably weren’t thrilled to see golf’s second-highest-profile player “standing in front of the media and addressing questions related to an insider trading investigation while wearing a KPMG hat and Barclays logo on his shirt.”

Then again, while several of Tiger Woods’ sponsors bailed on him following revelations of his serial adultery in 2009 — a transgression some may see as even hotter to handle than insider trading, even though only the latter is illegal — Woods managed to hold onto some others, including Nike, with its $30 million-plus annual investment in the longtime top-ranked golfer. In fact, by 2013, according to Golf Digest, Woods pocketed $71 million in off-course earnings, though that figure had been north of $100 million in the years immediately preceding his fall from grace.

Like Woods in that innocent time of yore, Mickelson, until the past few days, was viewed as a golden boy by his sponsors. His reputation has been as pure as Derek Jeter’s; among American sports stars today, few if any approach the do-no-wrong status those two have enjoyed.

This begs a question: are corporate sponsorships of professional athletes worth the potential heartburn? If Phil Mickelson isn’t a safe bet, is there any such thing? If a sponsor is thinking about pulling the plug on its investment at the first hint of scandal — Mickelson hasn’t been charged with any wrongdoing, almost three years after the trades in question were transacted — might the sponsorship have been a questionable strategy to begin with?

You can bet the CFOs of Mickelson’s sponsoring companies are in pow-wows with their marketing leaders right about now, searching for answers to those questions and the most basic one of all at the moment: should we hang in or get out? That’s a dicey one. Either option could make them look bad. Would you rather be seen as an unfair, thoughtless knee-jerker (as most of Phil’s millions of fans probably would see you), or as tolerant of insider trading?

It’ll be interesting to see, especially if charges against Mickelson do arise, whether the appeal of sponsoring athletes will wane as a result. In the long run, probably not too much, I’d say. In the short run, companies may want to sit on the sidelines for awhile and think about their next shot.