Katheryn McCarthy is counsel in Mayer Brown's Los Angeles office and is a member of the Real Estate group. Katheryn’s practice includes a broad spectrum of transactional real estate law, including representing institutional lenders, life insurance companies, residential developers, venture capital firms, small businesses and non-profits in the acquisition, disposition, leasing and financing of office, retail, hospitality, and residential properties located throughout the United States, as well as joint ventures, workouts, and foreclosures related to the foregoing. Prior to joining Mayer Brown Katheryn worked at another major international law firm, and served as an extern to Judge Kim McClane Wardlaw, United States Court Appeals for the Ninth Circuit.

Katheryn received the Outstanding Young Lawyer Award from the Real Property Section of the Los Angeles County Bar Association in 2010.


  • Represented an insurance company lender in numerous loan modifications related to the impacts of COVID-19.
  • Represented an insurance company lender in a $300 million mortgage loan secured by an outdoor mall and first class office property.
  • Represented an insurance company lender in a $175 million mortgage loan secured by a luxury resort.
  • Represented an institutional lender in the origination and subsequent upsize of a $220 million mortgage loan secured by a downtown Los Angeles high rise building.
  • Represented an institutional lender in a $360 million mortgage loan secured by a high profile outdoor mall in Los Angeles.
  • Represented an institutional lender in a $368 million portfolio mortgage loan secured by office properties.
  • Represented an institutional lead lender in the restructuring of a $98 million construction loan in receivership.
  • Advised an institutional investor in the assessment of “fix n flip” loan forms, in connection with the potential acquisition of a loan portfolio.
  • Represented an investor in assessing multiple complex development projects.
  • Represented an investor in establishing a $100 million “platform” for investments with an identified partner.
  • Represented an investor in assessing and amending multiple joint venture agreements to account for changed circumstances such as manager default and additional preferred equity “bail out” contributions.
  • Represented multiple homebuilders in the acquisition of raw land for development.
  • Represented the purchaser of a manufacturing business in negotiating a single tenant lease for continued operation of the existing facility.
  • Represented a publicly-traded real estate investment trust in negotiating multiple site leases with major supermarket chains.
  • Represented an institutional lender in originating a mortgage loan to a vacation club secured by vacation club properties, including (in conjunction with bankruptcy attorneys) through subsequent bankruptcy of the vacation club borrower and full repayment of secured debt.
  • Represented an institutional lender in negotiating a forbearance agreement and deed in lieu of foreclosure for a mixed use property in Oregon.
  • In conjunction with a litigation team, represented an institutional lender in the judicial foreclosure of a mortgage loan secured by a hotel.
  • Represented an investor in the purchase of a defaulted mortgage loan from an institutional lender and subsequent foreclosure of the security instrument.


University of Southern California Gould School of Law, JD
Order of the Coif; Staff, Southern California Law Review

University of Notre Dame


  • California


  • Consultative Board for Assumption of the Blessed Virgin Mary School in Pasadena from 2012-2017
  • Board of Directors for Sierra Madre Girls’ Softball Association from 2019-2021
  • Odyssey of the Mind Coach 2019-2021   
  • California Real Estate Broker's License