Tim Kohn, Vice President, heads Dimensional's US defined contribution practice, coordinating the sales and service for corporate, platform, and advisor-sold business. In this role, Tim works with clients and industry partners to market, research, and implement new defined contribution solutions. Tim leads Dimensional's DC efforts with academia, industry partners, and key stakeholders, and he also serves as executive editor for the firm's defined contribution client newsletter. Prior to joining Dimensional, Tim served as the head of DC Sales and Service and chief defined contribution strategist for Barclays Global Investors (now BlackRock). Tim received his BA in business economics from the University of California, Santa Barbara, and completed his MBA at the University of San Francisco, and also maintains a Master's of Science in personal financial planning. Tim is FINRA Series 7, 24, and 65 licensed, and a Chartered Mutual Fund Counselor.

As a Vice President in Research, Dave Twardowski leverages his background in statistical modeling, algorithms, and coding to provide solutions to a range of projects involving Dimensional's fixed income and equity portfolios, target date retirement products, and algorithmic trading strategies.
 
Prior to joining the firm, Dave worked for General Electric Aviation developing flight control algorithms for Black Hawk helicopters. He was also an adjunct staff member of the Institute for Defense Analyses, where he led a project addressing national security issues.
 
He received his PhD in computer science and engineering from Dartmouth College in 2011. He also holds an MS in mechanical engineering from the University of Michigan and a BS from the University of Rhode Island, where he graduated as salutatorian of mechanical engineering. Dave is also Series 7 licensed.