Mathias Kondolf was also a heavy stockholder, director, and one of the originators of the Rochester Co-operative Foundry and the German Insurance Company; he would long be associated with the former, and of the latter he would remain a director of until his death.  Soon after settling the stave business, he founded the Genesee Brewing Company in 1878.

He served as the president of Genesee Brewing Company until 1888, when it passed into the hands of an English syndicate controlling this and the Bartholomay breweries, under the name of the Bartholomay Brewing Company, of which Mr. Kondolf was a director. Retaining his interest in the new corporation, he caused the merging of the Genesee Brewery and the Rochester Brewery.

Kondolf was also an extensive dealer in real estate. He was the pioneer in securing pure ice from Hemlock Lake water for the city of Rochester in 1883, and has remained identified with that business under the name of Kondolf Brothers.  The company has had several imitators since.

In about 1885 he organized the Standard Sewer Pipe Company with a capital of $100,000, and has continuously been its president. He had been a director in the German American Bank since its inception, was for five years a member of the Board of Health.

Mathias Kondolf was married twice and had thirteen children living.

The current ownership company of Genesee Brewing employees over a 1,000 individuals with over a few hundred belonging to the Genesee Brewing segment and its headquarters in Rochester.