Portfolio Management Services (PMS) are professional investment services where expert managers handle a personalized investment portfolio (stocks, bonds, etc.) for high-net-worth individuals (HNIs), offering tailored strategies and direct ownership of securities, unlike mutual funds where money is pooled. PMS aims to maximize returns by creating custom strategies aligned with an investor's unique goals and risk tolerance, but requires a high minimum investment (typically ₹50 lakh in India) and involves steeper fees.