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Josh Walsh

Josh Walsh is the co-founder and chief executive of BranchLab, a New York-based company that applies artificial intelligence to healthcare advertising data, and is a two-time advertising technology entrepreneur [1][2][3]. He first built AdTheorent, an advertising technology firm he co-founded in 2011, which went public in 2021 and was later sold to Cadent [5]. Within AdTheorent, Walsh created and led AdTheorent Health, a specialized demand-side platform built to serve pharmaceutical and healthcare marketers, a division he describes as having become a significant contributor to the company's earnings and a fast-growing part of the business [4][5].

Through running AdTheorent Health, Walsh said he gained close exposure to the marketing operations of some of the largest pharmaceutical companies and concluded that the specialized DSP addressed only a narrow slice of a much larger inefficiency [4][5]. He has argued that the broader pharmaceutical commercialization process, including patient population modeling, healthcare-provider modeling, audience creation and deployment sizing, remains largely manual and offline, often taking three to nine months, while post-campaign measurement is similarly slow and provides limited basis for decision-making [4][5]. He has drawn a connection between improving this system and public health, contending that because pharmaceutical marketing can at most encourage a patient to consult a doctor rather than sell a drug directly, and citing academic research linking more doctor-patient conversations to better outcomes, a faster and more efficient marketing system should be expected to produce better health outcomes, while failure to modernize it risks the opposite [4][5].

Walsh left AdTheorent on January 31, 2024, and incorporated BranchLab two days later, on February 2, 2024 [4][5]. He has framed BranchLab's opportunity as analogous to the one he pursued earlier in mobile advertising: just as AdTheorent, which he characterizes as an early mobile DSP, moved ad buying away from offline transactions with ad networks and app developers, BranchLab aims to bring pharmaceutical audience data and measurement processes online, replacing offline audience vendors that Walsh says still operate much like the ad networks of 15 to 20 years ago, complete with manual ordering by phone or email and heavy travel budgets [4][5]. He has described BranchLab's approach as skipping the SaaS-era software cycle entirely and building directly with AI-driven, agentic tools instead [4][5].

Walsh has also discussed how his approach to building a company changed the second time around, citing more disciplined fundraising practices and an easier ability to recruit experienced talent compared to his first venture [4][5]. He pointed to BranchLab's chief technology officer, Dan Parks, previously founder of mobile ad tech company Placecast and later a technology leader at Ericsson and Amazon Prime Video, and head of AI Cat Drake, formerly head of computational biology and data science at Verily, Google's health-data affiliate, as examples of the caliber of hires he has been able to attract [4][5]. He has said that, beyond credentials, he now weighs whether candidates have direct startup experience, describing the day-to-day reality of startup work as considerably harder than it might appear from the outside [4][5].

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Josh Walsh argues that pharmaceutical commercialization work, including patient population modeling, HCP modeling, audience creation, deployment sizing, and measurement, remains offline and manual, often taking three to nine months, a system he calls inefficient and slow [1][2]. He draws a direct parallel to the ad network era of 15 to 20 years ago, noting that large audience vendors still package and resell data offline via phone calls and emails, and he sees an opportunity to skip the traditional SaaS cycle entirely by building directly with AI agentic tools [1][2].

His core thesis links better advertising infrastructure to public health: since pharma marketing can only encourage someone to talk to a doctor rather than sell drugs directly, and academic work suggests more doctor-patient conversations lead to better health outcomes, improving the efficiency of this system should improve health outcomes, while failing to modernize it risks degrading them [1][2]. He also emphasizes that founders returning to ad tech in the AI era benefit from how much faster building and prototyping has become [1][2].

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