Mark co-authored the Chicago Bar Association "Legal Opinions in Secured Real Property Transactions" which is the definitive legal opinion used in Illinois. He also was a member of the ABA Subcommittee that prepared the Real Estate sub-accord for use in conjunction with the so-called "Silverado" opinion. He is a frequent speaker before trade and professional groups on matters of state and federal legislation, multi-family housing financing, and commercial real estate lending topics.