Exxon shares slipped a fraction in pre-open trade on Wednesday ahead of the company's annual shareholder meeting that's expected to be its most contentious in years.

The worm may be finally turning at Exxon as a handful of influential institutional owners are putting pressure on ExxonMobil  (XOM - Get Report) to adopt a more transparent policy about its prospects under stricter environmental rules.

The issue will come to a head on Wednesday when the company holds its first annual meeting under the leadership of CEO Darren Woods, who took over the reins when former CEO Rex Tillerson left the company to become the U.S. Secretary of State.

Exxon shares dropped 25 cents or 0.3% to $81.10

Last week The Wall Street Journal reported that the energy giant is getting pressured on the issue from BlackRock (BLK - Get Report) and Vanguard Group, two large holders said to be considering a vote for an investor plan that would pressure Exxon to conduct climate stress tests to determine how environmental regulations impact its oil asset value.

Fidelity Investments and the California Public Employees' Retirement System are also said to be pressuring Exxon on climate change and environmental issues.

Exxon is urging investors to vote against the proposal. Should it pass, the measure would be a strong signal that investors want greater disclosure of the threats climate change poses to business.

And, low carbonExxon may have telegraphed its more general take on environmental issues when CEO Woods last week penned a letter to President Donald Trump urging him to keep the U.S. in the global Paris accord regarding climate change.

"Exxon Mobil maintains the view that the U.S. is well positioned to compete within the framework of the Paris Agreement with low-carbon resources such as natural gas, as well as innovative private industries including the oil, gas and petrochemical sectors," Woods wrote.

He went on to argue that remaining in the agreement would give the U.S. a "seat at the negotiating table to ensure a level playing field" for all energy sources.

On Thursday, 22 Republican senators sent a letter to Trump calling for the U.S. to pull out of the deal.

The Paris Agreement is within the UN's Framework Convention on Climate Change dealing with greenhouse gasses emissions reduction, adaptation, and finance starting in 2020.

As part of the deal, the U.S. pledged to reduce its emissions by between 26% and 28% from 2005 levels by 2025.

Woods is also likely to hear plenty about his own pay as well.

On May 19 proxy advisory firm ISS said sharehiolders should vote against the company's proposed pay package and called the company's remuneration policy out of date and not within industry standards.

"Exxon's executive pay program has remained largely unchanged for the better part of a decade. What has not remained constant over this period, however, are prevailing market practices and investors' expectations around executive compensation and related disclosure," ISS wrote in its report.