GLG (Gerson Lehrman Group, Inc.) is a financial and global information services consulting company headquartered in New York City.

[3] GLG's experts include asset managers, investors, consultants, physicians, scientists, engineers, lawyers, senior current and former c-level executives, and former government members.

[13][14] GLG, initially funded by friends and family, was formed as a publishing house to produce industry guidebooks for institutional investors.

However, the founders discovered that their clients wanted to talk directly to experts in casual conversations, rather than reading formal written reports.

[16] The expert network business model has drawn scrutiny for concerns relating to adherence to disclosure rules and insider trading within the investment industry.