In many cases, the network is driven by firsthand knowledge. Other times, it can be pure speculation. Allegations are often made anonymously and can quickly spread in online forums, damaging reputations before the accused can defend themselves. Men targeted by whisper networks complain of being subject to vigilantism and public shaming; some have threatened legal action.

At Bear Stearns — which was sold to JPMorgan Chase in 2008, during the financial crisis — the Glass Ceiling Club would warn others about the senior manager who had a history of affairs and a tendency to relocate his previous liaisons to remote offices, recalled Ms. Sherry, who last year published a semi-autobiographical novel, “Opening Belle,’’ about her experiences.

The women in the whisper network “weren’t best girlfriends,’’ Ms. Sherry said.

“What we did have in common was that we were ambitious professionals with the common goal of a more equal place of employment and so yes, that included our perplexity over outrageous behavior that went unchecked.“

Two decades later, fewer than two in 10 female harassment victims ever file a formal complaint, according to the Equal Employment Opportunity Commission.

The reluctance stems in part from the risks associated with reporting harassment, including fear of retaliation, according to The Harvard Business Review. Many women have reported being fired or sidelined at work after speaking up and labeled troublemakers while their tormentors face few, if any, consequences.

But when the whisper network moves onto social media platforms, accusations can gather momentum and quickly yield results.

In early October, a number of women came forward on Twitter to accuse Andy Signore, the creator of the popular YouTube series “Honest Trailers” and “Screen Junkies,” of sexual harassment.