Equitable Holdings Inc. and its AllianceBernstein Holding LP said Ramon de Oliveira had resigned as independent chairman of both companies after engaging “in communications that were inconsistent with” their standards.

Equitable and AllianceBernstein said in Friday filings with securities regulators that they had replaced Mr. de Oliveira with Joan Lamm-Tennant, an Equitable director since January 2020.

In...

Equitable Holdings Inc. and its AllianceBernstein Holding LP said Ramon de Oliveira had resigned as independent chairman of both companies after engaging “in communications that were inconsistent with” their standards.

Equitable and AllianceBernstein said in Friday filings with securities regulators that they had replaced Mr. de Oliveira with Joan Lamm-Tennant, an Equitable director since January 2020.

In a news release, Equitable said the departure was “unrelated to the Company’s operations, financial integrity or controls.” A spokeswoman with AllianceBernstein, an asset manager, referred questions on Mr. Oliveira’s departure to Equitable. An Equitable spokesman said the company wouldn’t elaborate on the nature of the communications. Mr. de Oliveira couldn’t be reached for comment.

France’s AXA SA spun out Equitable Holdings, with its majority stake in AllianceBernstein, in 2018. Equitable continues to own a majority of the asset manager. In 2019, Mr. de Oliveira was named independent chairman of both companies.

Mr. de Oliveira has also served on AXA’s board, and by late Monday afternoon the insurer’s website still listed him as a director. A representative for AXA said the company didn’t have an immediate comment.

Mr. de Oliveira’s departure comes less than five years after AXA ousted AllianceBernstein Chief Executive Peter Kraus and nine of the asset manager’s board members. The French company tapped former JPMorgan Chase & Co. executive Seth Bernstein as Mr. Kraus’s replacement. Mr. de Oliveira, a former colleague of Mr. Bernstein’s at JPMorgan, joined AllianceBernstein’s board in 2017.

Ms. Lamm is an adviser to numerous private-equity and venture-capital firms focused on insurance-technology startups. She is a former executive at consulting and insurance brokerage firm Marsh McLennan, where she headed its Enterprise Risk Management and was chief economist.

Equitable shares fell 0.3%, while AllianceBernstein rose 1.2%.

Thomas Gallagher,

a stock analyst with Evercore ISI, said Equitable’s statement gives “us comfort that the resignation was not due to any adverse financial impacts at the company.”

Mr. Gallagher said Ms. Lamm-Tennant’s experience in risk management and role in shaping Equitable’s environmental, social and governance strategy are important “in the current economic and social climates.”

The board will lose “valuable investment and capital markets experience with Mr. de Oliveira’s departure, though a strong management team and significant risk management expertise on the board give us confidence in Equitable’s current trajectory,” Mr. Gallagher wrote in a research note to clients.

Starting in 1977, Mr. de Oliveira spent 24 years at J.P. Morgan & Co., rising through the ranks. He became head of global equities in 1991 and later directed the bank’s stock-underwriting operation. He left the newly merged JPMorgan Chase in 2001 as then-head of its investment-management and private-banking group. He subsequently was a managing director of New York-based consulting firm Investment Audit Practice LLC.

Write to Leslie Scism at leslie.scism@wsj.com and Justin Baer at justin.baer@wsj.com