Herb Sandler, a banker and philanthropist who with his wife, Marion, provided the initial financing for ProPublica, the nonprofit investigative-reporting organization that seeks to be an alternative model for sustaining vigorous journalism, died on Wednesday at his home in San Francisco. He was 87.

His family announced the death. The cause was not given.

Mr. Sandler and his wife, who died in 2012, made their fortune by building a small bank in Oakland, Calif., into Golden West Financial, a multibillion-dollar lender. They had long supported progressive causes when, in 2007, their Sandler Foundation provided almost all of ProPublica’s initial funding.

ProPublica, which often collaborates with traditional news organizations, including The New York Times, has since won five Pulitzer Prizes and numerous other awards.

Mr. Sandler was its board chairman from its beginning until 2016. In the last several decades, with print advertising evaporating, many newspapers have closed or cut staff, a worrisome development to Mr. Sandler.