The Sustainability Accounting Standards Board (SASB), which hopes to standardize how companies report their environmental and social impact, said it has received a flood of new interest since investment giant BlackRock Inc touted it an open letter to CEOs this year.

The San Francisco-based nonprofit, which has received funding from liberal billionaires Michael Bloomberg and Tom Steyer—both of whom recently withdrew as contenders for the Democratic presidential nomination—said its website drew 1,092 new users per day in February, more than double the daily rate last year, with many of the visits from accountants and lawyers who oversee corporate filings.

SASB CEO Janine Guillot said the group is now working to translate the new traffic into more data reporting. SASB counts 139 companies worldwide that report data in accordance with its guidelines. Guillot said she expects that could rise to as many as 300 by next year.

"It is surprising how much a little letter from Larry Fink can generate," said Guillot, referring to BlackRock's CEO.

Fink's annual missive to corporate CEOs in mid-January asked that all companies in which BlackRock invests by year-end “publish a disclosure in line with industry-specific SASB guidelines," or something similar, arguing in favor of SASB's “clear set of standards."

State Street Corp., another large asset manager, also plugged SASB for promoting material disclosures in a recent open letter.

Who’s Behaving Badly?

SASB is one of several organizations—another is the Global Reporting Initiative (GRI)—seeking to cut through a fog of uncertainty on how to measure companies' progress on sustainability matters, at a time of mounting concern among investors over climate change and other issues.

A lack of widely adopted reporting standards on sustainability metrics up to now has yielded alarming results for ratings firms seeking to rank companies on their performances, complicating the task for investors trying to build a truly green portfolio.

In a study published last year, for example, MIT Researcher Roberto Rigobon found the scores that companies received from five top environmental, social and governance (ESG) ratings firms on greenhouse gas emissions had an average correlation of 0.13—remarkably low considering the 0.9 level of major credit ratings services.

"This is disturbing," Rigobon said. "We need to be able to figure out as a society who is behaving badly and who is not."

Finding a set of uniform reporting standards for sustainability could solve the problem in the same way as financial accounting standards have made it easier for investors to assess a company’s financial health, according to Robert Fernandez, vice president at Breckinridge Capital Advisors and a member of SASB's investor advisory group.

"Maybe we wouldn't have to rely on the ESG raters as much if there were more data and we could do more of the analysis ourselves," he said.

SASB rival GRI asks for a wider range of details in its sustainability reporting guidelines than SASB's industry-specific requests. GRI is used by about 4,000 companies, according to research firm Corporate Register, though the figure has grown little in recent years.

GRI CEO Tim Mohin said he worries investors and companies are going to lean toward SASB's narrower reporting guidelines, instead of GRI's more thorough ones. If SASB became dominant, he said, "It could become a massive rollback of ESG disclosure."

BlackRock did not make executives available to discuss why they favored SASB. BlackRock has a representative on the board that sets SASB standards, and executives from BlackRock and from State Street serve on SASB's investor advisory group.

Paperwork Overload

Some companies report against both SASB and GRI standards, or plan to do so soon, including Vornado Realty Trust, JetBlue Airways Corp. and Duke Energy. Duke executives said they hope the standards eventually converge.

"We just want to have consistency, that's the main goal," said Duke CFO Steve Young.

For other companies, SASB's simplicity makes it a favorite. Sanderson Farms Inc. of Laurel, Mississippi, said last month it will adopt SASB guidelines, even after shareholders rejected a resolution seeking partial SASB reporting.

CFO Mike Cockrell said the company made the decision after BlackRock and other investors suggested the step. He said he also hopes the move will forestall shareholder requests for other, more detailed disclosures including from the GRI.

"I could have a staff of 30 people working 40 hours a week for 52 weeks and still not be able to complete some of these reports," he said.

Andrew Behar, CEO of environmental resolution sponsor As You Sow, said he credits BlackRock and State Street for boosting SASB, even if ideally companies would also provide a GRI report.

For now, he said, "We got what we wanted."