LLR Partners, a Philadelphia investment firm, has bought a minority stake in Center City-based Professional Capital Services, an 85-person, "no pay-to-play" investment-software recordkeeping platform that automates retirement plans for money managers and their clients.

The firms would not say how much LLR is pumping in to expand PCS. LLR typically invests at least $15 million, up to $100 million, into firms with yearly sales of at least $20 million.

PCS expects that LLR cash and financial-tech experience "will help accelerate" new products and sales, founder and CEO Mark Klein said in a statement. Founded in 2001, PCS says it has more than 2,000 investment clients, from independent investment advisers to broker-dealer firms, covering 150,000 retirees.

LLR was attracted to PCS's "transparent and commission-free" approach to money management, which gives users "price transparency" and avoids conflicts of interest among financial professionals selling services to clients, LLR vice president Ryan Goldenberg said in a statement.

Founded by Philadelphia property investor and Valley Forge casino owner Ira Lubert, investment banker Seth Lehr and accountant Howard Ross, LLR says it has raised $3 billion from investors, including Pennsylvania state pension funds, since 1999.