This study uses a controlled experiment to examine the trade‐off between managers’ use of non‐GAAP and GAAP earnings to satisfy market expectations and how this relationship can be moderated by both formal and informal regulatory attention to non‐GAAP earnings. Our key takeaway is that allowing financial reporting discretion in an alternative disclosure channel, that is, non‐GAAP earnings, can reduce firms’ opportunistic GAAP reporting. However, statements by regulators about increased attention to non‐GAAP earnings constrain this channel, and this can result in more aggressive GAAP earnings management and reduced GAAP earnings quality. We triangulate these findings with a survey and archival analyses and find results that are consistent with this primary message. Our study provides evidence relevant to standard setters and regulators that non‐GAAP measures may serve an important role even if they can be used opportunistically.