The New York Times Company has been fighting a union drive led by its tech workers for months, and things have escalated recently, with the Guardian breaking the news that management is fiercely opposed.

Some of the Times’ own shareholders are stepping in and telling the media company to let the union process take its due course.

Today, the investment management firm Trillium Asset Management sent a letter to New York Times Company CEO Meredith Levien urging management to take a more neutral stance toward unionization efforts among the company’s tech workers and to cease actions that could violate federal labor law. Trillium, “an impact-driven, ESG-focused firm,” sent a similar letter to Starbucks in early December after a union push among a small number of workers.

The letter to the New York Times Company, signed by a coalition of investors representing over $1 trillion in assets under management, states: “These investors believe that collaborative partnership between companies and unions facilitates positive labor relations by representing the interests of employees and fostering effective feedback loops between employees and management. Effective workforce management offers benefits including lower attrition, higher employee engagement, and in turn, higher quality products and services.”

Jonas Kron, Trillium’s chief advocacy officer, says that an “accumulation of reports about behavior that falls within the classic definition of anti-union activity” spurred the letter.

Last April, tech workers at the Times announced that they had formed the Times Tech Guild. The company decided against voluntarily recognizing the union, which led the Guild to formally file for an election with the National Labor Relations Board that covered five major job functions within the company: engineers, designers, product managers, project managers, and data analysts.

The company argued that the union improperly included groups of employees with different working conditions, a claim rejected by the NLRB in a ruling last month that has since allowed election proceedings to continue.

Ballots were sent out on January 24, are due by February 28, and will be counted by March 7. More than 600 employees are eligible to vote.

Bon Champion, a senior product designer on the New York Times News app and member of the Times Tech Guild, notes that Times management has engaged in anti-union activity since the union went public. Most recently, management has taken to posting memos in read-only Slack channels urging employees to vote no in the coming election. “We can’t respond, we can’t actually engage in a discussion,” he says.

“These kinds of communications have been pretty steady for the last several months, but really ramped up after the election was set in the last couple of weeks.”

Champion says the Guild is pleased with Trillium’s letter: “We agree with the investors that the company is stronger when workers, whether they are writing code or writing journalism, enjoy strong common sense job protections.”

In a statement shared with Fortune by Danielle Rhoades Ha, the vice president of communications at the New York Times Company, the company affirms: “We are not against unions. But we do not believe a union would be best for the individuals or teams in the proposed tech and digital product unit. The success of digital product development relies on collaboration, speed and constant experimentation, all of which a collective bargaining arrangement could stifle.”

Both Champion and Kros note the disjunction between the New York Times Company’s actions and the values espoused by its editorial board. Champion points to a 2007 op-ed titled “The Right to Organize” that advocates for companies to voluntarily recognize unions formed by the majority of their employees.

“I think we’re seeing more and more investors and consumers and corporate leadership becoming increasingly aware of the way a company talks about what is important to the company, and then what the company does,” says Kros.

If the Tech Guild wins its  election in March, it will represent the largest union in tech with bargaining rights. Currently, the title for largest tech union is held by the Alphabet Workers Union, which represents Google employees. As a minority union, the AWU is not registered with the NLRB and cannot engage in collective bargaining.

This story was originally featured on Fortune.com