Sik Ahn is the co-chairman of Hankyul Law Group and his practice is mainly focused on corporate matters and finance, especially in the areas of corporate restructuring such as M&A and corporate rehabilitation, venture business, inducing investment, asset-backed securitization, private equity fund formation, and compliance, etc. Sik Ahn has also served as a member of the board of directors of Korea M&A Association and advised numerous government agencies.

In addition, Sik Ahn has given lectures on corporate law and mergers and acquisitions at numerous institutions such as Seoul National University Graduate School of Business for its Global MBA program, Korea Development Institute, Korea Asset Management Corporation, Korea Management Association, and Small and Medium Business Corporation. Sik Ahn published several articles in the Law Times and Business Law, etc. and also published a book on mergers and acquisitions.