# Michael Rubenstein

> Michael Rubenstein is the New York-based co-founder, co-CEO and board director of Firsthand, which builds AI Brand Agents for marketers and publishers. He previously founded and led DoubleClick Ad Exchange and served as president of AppNexus, combining advertising marketplace experience with an interest in company culture, partnerships and mentoring entrepreneurs.

- **Role:** Co-Founder, Co-CEO and Board Director at Firsthand
- **Organizations:** Firsthand, AppNexus, DoubleClick, Google, FloNetwork, Teikametrics
- **Education:** BA, political science, McGill University, MBA (executive program), Columbia Business School
- **Known for:** Founded and led DoubleClick Ad Exchange., Helped grow AppNexus as president and board member; AT&T acquired it in 2018., Co-founded Firsthand, which secured a $26 million Series A announced in March 2025.

## Career timeline

- **While at McGill** — Started a marketing and advertising business as an undergraduate.
- **After graduation in 1997** — Joined the Toronto email-marketing startup Media Synergy, later renamed FloNetwork.
- **Early 2000s** — Entered DoubleClick through its acquisition of FloNetwork and moved to New York.
- **2004** — Completed his MBA at Columbia Business School.
- **Before 2008** — Founded and served as general manager of DoubleClick Ad Exchange.
- **2008** — Google completed its acquisition of DoubleClick; Rubenstein subsequently worked at Google.
- **2009-09** — Joined AppNexus as president.
- **2018** — AT&T acquired AppNexus, where Rubenstein continued as president.
- **2023** — Co-founded Firsthand with Jonathan Heller and Wei Wei.
- **2024-02** — Firsthand emerged from stealth and announced seed backing led by Radical Ventures.
- **2025-03** — Firsthand announced a $26 million Series A.
- **2026-09** — Joined IGN at IAB PlayFronts to demonstrate an adaptive AMD advertiser experience.

## Achievements

- Founded and led DoubleClick Ad Exchange.
- Helped grow AppNexus as president and board member; AT&T acquired it in 2018.
- Co-founded Firsthand, which secured a $26 million Series A announced in March 2025.

## Latest updates

- **2026-09** — Discussed Firsthand’s adaptive advertising approach in a Beet.TV interview at IAB PlayFronts; Firsthand described its IGN partnership and AMD campaign demonstration.
- **2025-11** — Appeared on The Media Copilot to discuss AI Brand Agents and the adaptive web.
- **2025-10** — Discussed building Firsthand, risk and leadership with Mike O’Sullivan on The Big Impression.
- **2025-03** — Firsthand announced a $26 million Series A led by Radical Ventures.

## Links

- Website: https://www.firsthand.ai/
- LinkedIn: https://www.linkedin.com/in/mrubenstein99/
- Twitter/X: https://x.com/mrubenstein99

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Profile page: https://yespress.io/michael-rubenstein
Published by YesPress — https://yespress.io
Last updated: 2026-10-09