.406 Ventures

.406 Ventures is a Boston firm with roughly one and a half billion dollars under management, and its identity is shaped by a Boston-specific theory of how to invest in healthcare. The firm has historically backed three intersecting verticals: healthcare, data and AI, and cybersecurity. The healthcare practice draws on Boston’s unusual concentration of academic medical centers, payer headquarters, and health-IT companies, and the firm has built a partnership and operating network optimized for selling into that ecosystem. The fund invests at seed through Series B with check sizes in the five to twenty-five million dollar range, which puts it in the rare position of being able to lead seed rounds at meaningful size and follow on through Series A and B without dilution-inducing reserves drag. For digital health, AI-in-healthcare, and health-IT founders selling into health systems and payers, .406 Ventures is one of the better-known Boston names with a track record of backing companies at the inflection between clinical pilots and enterprise rollout.

The investment thesis sits squarely in business-to-business healthcare technology. The firm is interested in AI-enabled clinical software, in health-IT platforms that automate administrative or clinical workflows, in tech-enabled care delivery models that scale through software rather than through pure operational expansion, and in healthcare cybersecurity. What the firm is generally not chasing is consumer digital health, capital-intensive therapeutics, or hardware-heavy medical devices. The discipline is intentional. Boston has plenty of capital for therapeutics; .406 has positioned itself for the software side of the healthcare stack, where the unit economics resemble enterprise SaaS and where the firm’s enterprise-sales playbook compounds across portfolio companies. AI focus is genuine and central to the current investing posture, with the firm explicit that AI-native applications in healthcare and in cybersecurity are central to recent and forthcoming activity. Founders should expect diligence to probe deeply on enterprise sales motion, on regulatory and compliance posture in HIPAA and adjacent frameworks, and on the data strategy that makes the AI improve over time rather than merely function on day one.

This profile does not include a specific list of portfolio companies. Founders should consult the firm’s portfolio page directly and pay attention to which healthcare investments have moved from seed through Series B inside the .406 portfolio. That progression is the cleanest indicator of which companies the partnership has continued to back with conviction, and which companies have become reference points for the firm’s thesis. Founders should also study which investments have crossed into commercial relationships with major Boston-area health systems and payers, since those relationships are often quietly facilitated by the firm’s network.

The check size range and stage focus position .406 as a credible lead at seed and Series A, with continued participation through Series B. The seed checks at the upper end of the range are meaningfully larger than what most institutional seed funds will write, which gives founders a way to build a smaller, higher-conviction syndicate at seed rather than assembling a long roster of small checks. At Series A and B, the firm participates as a lead or as a strong follow-on, and its reserves are sized to support pro-rata across multiple rounds. For founders, the implication is that an early .406 round leaves room for major Series A and B leads to come in without crowding the cap table, while still providing meaningful institutional support across the early life of the company. The firm syndicates with healthcare specialists and with generalist East Coast and West Coast funds, and a led .406 round signals to other healthcare investors that the company has been vetted by partners with deep enterprise-sales pattern matching.

Team member names are not enumerated in the source data for this profile. Founders should consult the firm’s website to identify the current healthcare partners and pay attention to which have prior operating experience inside payers, providers, or health-IT companies versus which come from pure venture backgrounds. The firm has historically built a partnership weighted toward operators in healthcare and security, and decision-making is partnership-driven with a sponsoring partner shepherding deals through investment committee. Founders should plan for a single primary relationship with the sponsoring partner and should not expect the broader partnership to be deeply involved post-investment.

The most reliable path into .406 Ventures is a warm introduction from a Boston-area health-system executive, a payer-side leader, or a portfolio company founder. The Boston healthcare community is dense and well-networked, which means partner-level introductions are the dominant origination channel. Connections through Harvard, MIT, and the Boston-area academic medical centers carry meaningful weight given the firm’s geography. Cold inbound through the firm’s website is read and occasionally converts, particularly when the founder has prior commercial validation from a Boston-area health system or payer. Communication should be quantitative and grounded in enterprise sales metrics rather than narrative-heavy.

Founders should approach .406 when they are building B2B healthcare software with an enterprise sales motion, when they have at least early commercial validation from a health system or payer, and when they are raising seed through Series B. The firm is not the right fit for consumer digital health, for therapeutics, or for early-stage companies still searching for their first paying customer. It is an excellent fit for AI-enabled clinical and administrative software, for health-IT platforms with regulatory complexity, and for healthcare cybersecurity companies serving health systems and payers. The Boston network advantage is real and largely irreplaceable for founders selling into that ecosystem.