By Simon Jessop and Helen Reid

LONDON (Reuters) - A leading investor in German sportswear company Adidas said on Monday it plans to vote against the reelection of Chair Thomas Rabe at the company's annual shareholders' meeting on Thursday because he holds too many roles at other companies.

Despite being concerned about the so-called "overboarding" last year, Allianz Global Investors - the 13th biggest investor in Adidas, according to LSEG data - said it had supported Rabe's reelection on the basis that the company would find a replacement.

Since then, the company has not presented a successor or laid out a "convincing" succession plan, Allianz said in a statement.

"We want to understand the key competencies required for the incoming chair to effectively lead the board, as well as how the search process is managed," said Matt Christensen, Global Head of Sustainable and Impact Investing at AllianzGI.

"The incoming chair should possess strong leadership skills, industry experience, unquestionable independence, and enough time to lead the board, especially in times of crisis."

Rabe is Chief Executive Officer at both RTL Group and at Bertelsmann, the media conglomerate that owns RTL.

Adidas did not immediately reply to a request for comment.

AllianzGI's statement comes after leading proxy advisor Institutional Shareholders Services for the second year recommended investors vote against Rabe's reelection, saying he has too many roles at other companies and that the board is "insufficiently gender diverse".

Proxy advisor Glass Lewis recommended investors vote for Rabe's reelection, but that they reject Adidas' executive compensation, saying the company has not engaged sufficiently with shareholders after 41% of them voted against the remuneration report last year.

Adidas gave large severance payments of 7.2 million euros ($8.01 million) and 4.8 million euros to two departing executives last year, Glass Lewis said, after three big severance packages in 2023 and a payout of around 15 million euros to former CEO Kasper Rorsted in 2022.

"We remain troubled by the allocation of substantial severance payments following the dissent expressed by shareholders in the past two years," Glass Lewis said in its note to shareholders.

($1 = 0.8990 euros)

(Reporting by Simon Jessop and Helen Reid, Editing by David Evans)