Utilize the input text as a context reference, choose the right relationship between Highmark and Pittsburgh from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

On the commercial side, in Q2, we improve net coverage within two prominent regional commercial plans, Highmark Blue Cross Blue Shield and the University of Pittsburgh Medical Center or UPFC.

Answer: headquarters_location