MGNI vs PUBM: Which Is the Better Buy in 2026?

Same yardstick, side by side (as of August 2026). Valuation lined up like this is most meaningful for two names in the same corner of the market, which these are. Figures are approximate; verify before investing.

Reading it: MGNI is the cheaper of the two on forward earnings, but cheaper is not the same as better. Pair the valuation with growth (how far the forward P/E sits below the trailing P/E) and risk (beta) before you decide.

The metrics above tell you which is the marginally better business. The bigger risk for most people is not picking the slightly worse stock, it is over-concentrating. MGNI and PUBM share themes, so owning both, or adding either to what you already hold, can quietly push a large share of your portfolio into one bet.

This is the part a generic comparison page cannot answer, because it depends on what you own. Connect your brokerage and Walnut shows your real, combined MGNI and PUBM exposure, flags overlap with your existing positions, and tells you if adding one would tip you past a concentration you are comfortable with, read-only by default, with your login staying at your broker. Walnut is not an investment adviser.

Magnite is the largest independent omni-channel sell-side advertising platform, or SSP. Publishers plug their inventory into Magnite's technology to sell ads programmatically across formats and channels, and Magnite keeps a take rate on the ads that clear. It reports its business in two broad areas: CTV, which covers streaming and Connected TV inventory and is now the largest and fastest-growing part of the company, and DV+, which covers desktop, mobile, and web display and video. Being independent is central to the pitch: unlike Google or Amazon, Magnite does not own competing media, which it argues lets publishers trust it without conflicts of interest.

Full MGNI guide

PubMatic, Inc. is an independent, technology-driven company that operates a sell-side platform for digital advertising. Its software lets publishers, app developers, and streaming services (the supply side) sell their advertising inventory programmatically to advertisers and their demand-side platforms in real time. A key differentiator is that PubMatic built and owns its own infrastructure rather than renting cloud capacity, which management argues gives it cost and margin advantages at scale; the platform processes well over a trillion ad impressions per day. The business is exposed to the secular shift of advertising dollars into automated, data-driven channels, especially connected TV, online video, and commerce media.

Full PUBM guide

Both fit overlapping themes, but they are not interchangeable. The useful comparison is which set of drivers and risks you want exposure to.

• MGNI drivers: CTV and the shift of TV dollars to streaming; Marquee publisher relationships.
• PUBM drivers: CTV and online-video growth; Supply-path optimization and Activate.

A faster-growing, richer-valued name usually swings harder, so it suits a longer horizon and a higher tolerance for volatility; a steadier, more cash-generative business suits a more conservative or income-minded investor. The honest test is which set of risks you could hold through a drawdown: The central risk is that Magnite is a mid-cap ad-tech company whose revenue is tied to advertising cycles: ad budgets are among the first things cut in a slowdown, so results can be lumpy and CTV growth can decelerate. For PUBM, the dominant risk is competition and scale: PubMatic is a small independent SSP competing against far larger platforms, including Google's dominant ad stack and well-funded rivals like Magnite, in a market where the demand side (led by The Trade Desk) holds significant leverage.

Growth-minded investors who believe the theme has years to run tend to accept the richer multiple for more upside; value-minded investors lean toward the cheaper forward earnings and steadier profile. Pick MGNI if you believe its drivers more; PUBM if you believe its. Many investors hold both, but since they share themes, that is a concentrated bet, not diversification. Decide deliberately and check overlap. For the full detail, see the MGNI and PUBM guides.

MGNI. Figures are qualitative and tied to the asOf date; verify live numbers before acting. Magnite trades more on CTV growth, take rates, and adjusted EBITDA than on trailing GAAP earnings, which have at times been thin, so a simple P/E can be misleading. Because it is a mid-cap ad-tech name, results and sentiment can swing sharply around quarterly reports and shifts in the advertising cycle.

PUBM. Figures are approximate, qualitative, and tied to the asOf date; verify live numbers before acting. As a smaller-cap growth company, PubMatic's valuation hinges more on expected share gains in CTV and commerce media than on trailing multiples, and its quarterly results can be lumpy with the advertising cycle. Weigh the net-cash balance sheet and free-cash-flow generation against thin margins and the risk that emerging revenue lines fail to scale into a durable share of the business.

Headline figures (approximate, Jul 2026): MGNI shows revenue (ttm) In the roughly high-hundreds-of-millions range annually, with quarterly revenue growing at a modest overall rate as strong CTV offsets slower DV+, ctv growth CTV is the largest and fastest-growing segment, generally growing well ahead of the total company when political spend is excluded, profitability / adjusted ebitda GAAP results are thin or breakeven at times; management emphasizes non-GAAP EPS and adjusted EBITDA, which have been positive, balance sheet / debt Carries term-loan debt from prior acquisitions (SpotX era); has worked to reduce leverage and generate free cash flow; PUBM shows revenue scale First-quarter 2026 revenue was about $62 million, with roughly 13% year-over-year growth in the underlying business, ahead of company guidance, profitability Generated modest positive adjusted EBITDA and positive free cash flow in Q1 2026; margins are thin and can swing with ad volumes, emerging revenue Newer lines (CTV, commerce media, supply-path optimization) grew more than 80% year over year off a small base, a key growth signal, balance sheet Historically run with a net-cash position and no meaningful debt, which supports buybacks and investment through cycles.

MGNI and PUBM are related but distinct: same themes, different businesses and risks. Neither wins in the abstract; the right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme. Walnut can show your combined MGNI and PUBM exposure against your real portfolio. It is not an investment adviser.