As a serial entrepreneur, Mark built a real estate empire that in 2017 ranked as the fifth-largest brokerage in the US, with a sales volume of $14.1 billion. He established Morgan Lane in Marin County in 2006, led the company to acquire Pacific Union International (PUI) in 2009, and grew the company from $2.1 billion to that $14.1 billion mark in sales volume in nine years. In August 2018, PUI joined Compass, amassing 6,400 real estate professionals representing $28 billion in sales volume. As the President of Compass California and later Chief Real Estate Strategist for Compass, Mark's leadership and business experience helped the company excel with mergers, acquisitions, and expansion efforts. Today he is CEO of McLaughlin Ventures and a board member at Aidentified LLC.