The Justice Department has been investigating Andreessen Horowitz for nearly a year to determine whether the venture capital firm created an unlawful board interlock by placing two of its partners on the boards of competing data companies. The inquiry centers on Ben Horowitz's position at Databricks and Martin Casado's seat at Fivetran, with prosecutors examining whether these separate directors function as agents of the firm rather than independent corporate fiduciaries.

What Is a Board Interlock and Why Does It Matter?

A board interlock occurs when the same person, or representatives of the same organization, sit on the boards of competing companies. Section 8 of the Clayton Act, a foundational antitrust law, prohibits a person from serving as an officer or director of competing corporations. The Justice Department's legal theory suggests that an investment firm like Andreessen Horowitz can create an interlock by appointing separate people as its agents on rival boards, even if those individuals are different people.

This investigation is part of a broader Justice Department campaign against board interlocks. By March 2023, the department had unwound or prevented interlocks involving at least 13 directors from 10 boards, according to public statements. In most cases, the resolution involved a director resigning or the firm surrendering its appointment rights without any admission of liability.

What Would the DOJ Need to Prove?

To bring a Section 8 case against Andreessen Horowitz, the Justice Department would need to establish several key elements. First, prosecutors would have to prove that Databricks and Fivetran are legal competitors whose competitive sales exceed the thresholds set by Section 8. Second, they would need to demonstrate that Horowitz and Casado acted as agents of Andreessen Horowitz rather than as independent corporate fiduciaries making decisions in the best interest of their respective boards.

The investigation has not publicly established either of these points. The department has made no final decision, and the inquiry may ultimately end without any action taken against the firm. Neither Andreessen Horowitz nor Fivetran responded to requests for comment when the investigation became public, and Databricks declined to comment.

How Do Courts View the "Deputization" Theory?

The legal theory underlying this investigation, sometimes called the "deputization" theory, remains contentious among legal scholars and has weak grounding in some interpretations of antitrust law. An August 2023 analysis published in the American Bar Association's Antitrust Magazine concluded that the theory has limited support in the statute's language and history. A May 2023 analysis by lawyers at Cooley reached a similar conclusion, noting that the Justice Department's resignation campaign had produced no judicial decisions, leaving little precedent for an expanded theory.

The few court cases that have examined this issue have set a high bar for proving an interlock. In the 2003 Reading International case, a federal district court examining competing movie theater companies required proof that directors acted as "puppets or instrumentalities of the corporation's will." Affiliation or employment alone was not sufficient.

Steps the DOJ Takes When Investigating Board Interlocks

• Initial Inquiry: The Justice Department opens an investigation into whether separate directors of an investment firm serve as agents on competing company boards, examining their decision-making patterns and communications.
• Competitive Analysis: Prosecutors determine whether the companies in question are legal competitors and whether their competitive sales meet the statutory thresholds required under Section 8 of the Clayton Act.
• Agency Determination: The department examines whether the directors act independently or function as representatives of the investment firm, looking for evidence of control or coordination.
• Resolution Options: If the department finds sufficient evidence, it typically seeks a voluntary resolution such as a director's resignation or the firm's surrender of appointment rights, rather than pursuing litigation.

What Happened With Fivetran and dbt Labs?

The timing of this investigation is notable given recent corporate activity involving Fivetran. In October 2025, Fivetran announced an all-stock merger with dbt Labs, a data transformation company. Martin Casado, the Andreessen Horowitz partner under investigation, previously served on the dbt Labs board. The merger completed on June 1, 2026, and the Justice Department reviewed the transaction for several months before clearing it without conditions.

The separate interlock investigation into Andreessen Horowitz's board seats opened around the same period as the Fivetran-dbt Labs merger review and continued after the merger closed. This suggests the two inquiries are distinct, though they may have overlapping considerations regarding competition and corporate control.

How Does This Compare to Other Recent Antitrust Actions?

The Andreessen Horowitz investigation is not the first time the federal government has challenged board interlocks in recent years. In August 2023, the Federal Trade Commission proposed a consent action that would have barred Quantum Energy Partners from taking a board seat in a $5.2 billion transaction. The agency approved the final order later in 2023, concluding its first Section 8 case in 40 years. That matter involved direct competitors in Appalachian natural gas and included restrictions on information exchange.

The Quantum Energy Partners case represented a significant enforcement action, but it differed from the Andreessen Horowitz situation in important ways. The Quantum case involved a direct competitor and included concerns about information sharing, whereas the current investigation focuses on whether separate partners of an investment firm can create an illegal interlock through their individual board positions.

The outcome of the Andreessen Horowitz investigation could have implications for how venture capital firms manage their board representation across portfolio companies. If the Justice Department successfully establishes that separate partners can create an illegal interlock, it would expand the scope of Section 8 enforcement and potentially require investment firms to be more careful about placing multiple partners on boards of companies in related markets. However, legal experts emphasize that the theory remains narrow and fact-specific, dependent on proving both competition and control.