American companies appear to have found a solution to the white-hot political atmosphere in Washington – more disclosure.

More companies than ever are making efforts to fully disclose their political donations, according to a survey by Center for Political Accountability (CPA) and the Zicklin Center for Business Ethics Research at the Wharton School at the University of Pennsylvania.

Released in the run-up to the 2018 midterm elections, this years survey found 57 companies in the S&P 500 received scores for political disclosure and accountability of 90% or above, up from 50 last year and double the 28 companies that received that grade in 2015. Three companies received a 100% disclosure score, up from one last year.

More S&P 500 companies also had disclosure and accountability policies and practices that scored in the first and second tiers (100% to 60%), a total of 196 compared with 174 in 2015.

Bruce Freed, CPA president, said there were a number of factors driving the change – not least the politically charged atmosphere that has rent the US. “Companies recognise that political spending poses not just a reputational risk but a business risk,” he said.

“I can’t remember a more volatile midterm election season. Companies that spend political money in this climate are taking a risk of consumer blowback or even boycotts.”

Having a clear policy on disclosing political donations makes it easier for executives to say no to political action committees and others, he said, especially when some of those donors want the donations to remain private.

The rise has also been fueled by shareholder activism. On average 35% of shareholders voted in favor of motions proposing clear political donations disclosure policies last year, up from 30% the year before.

While Freed acknowledged that corporate money was still pouring into political campaigns, and the survey does not look at lobbying cash, he said it was now see transparency as a way to “enhance their reputations and to avoid blowback”.