(Reuters) -Institutional Shareholder Services (ISS) has asked BlackRock ( BLK ) investors to vote against the asset manager's executive compensation plans, escalating tensions after a narrow win last year for its top management's remuneration packages.

While BlackRock ( BLK ) gathered feedback in 2024 from its 50 largest shareholders after securing about 58% support for its compensation plan last year, its efforts to address their concerns fell short, proxy adviser ISS said.

After learning that some shareholders opposed one-time awards, the asset manager refrained from granting any in 2024, according to a proxy filing.

However, the company had not addressed how shareholders' feedback will inform future decisions around one-time awards, ISS said.

BlackRock ( BLK ) also engaged with investors to discuss the context behind a private markets-driven long-term incentive for CEO Larry Fink.

But the proxy adviser pointed out that the company had not provided assurances that such discussions would take place before any significant compensation changes in the future.

BlackRock's ( BLK ) annual meeting is scheduled for May 15. While the vote on management pay is not binding, significant opposition could still influence future decisions.

The company said it "aligns compensation with the successful delivery of long-term business goals," adding that 2024 was a milestone year for revenue, net inflows and other financial metrics. "We value the opinion of our shareholders and look forward to continued engagement," a BlackRock ( BLK ) spokesperson said.

Disputes between proxy advisers and financial heavyweights have escalated in recent years. ISS had also urged rejection of one-time stock awards to the top two executives at Goldman Sachs, but shareholders approved that last week.

Shareholder activist campaigns in North America fell 7% in the first quarter from the same period a year earlier, according to data from Diligent Market Intelligence.

However, the decline was less severe than in Asia, which saw a 37% drop.