Magnite: Strong Q3 CTV Growth Yet Valuation Stretched

What happened

Magnite reported Q3 2026 revenue up 20% year-over-year and adjusted EBITDA up 46%, driven by continued CTV momentum and political ad spend, with CTV accounting for 53% of ex-TAC. Management reaffirmed expectations of 25%+ CTV growth over the next three to five years and guided for FY2026 ex-TAC growth of 17%, adjusted EBITDA growth of 30%, and free cash flow growth of 60%. The company remains the largest independent supply-side platform, benefiting from the secular shift of TV budgets to streaming. Despite these robust fundamentals, the article highlights that the stock is expensive, trading at a valuation that reflects high expectations. This follows our earlier neutral assessment, where we noted valuation as a key risk, but the growth metrics surpass our previous assumptions.

Implication

The Q3 results and guidance confirm that Magnite is successfully scaling its CTV business and improving profitability, which strengthens the long-term growth story. However, concentration in CTV and reliance on large DSPs through supply-path optimization pose ongoing risks to take rates and growth sustainability. The stock's valuation, despite higher earnings, remains expensive relative to historical norms and peer multiples, limiting upside potential. Investors should look for a better entry point or further evidence of cash flow re-acceleration before adding positions. Current holders may maintain but should monitor SPO developments and CTV pricing trends closely.

Thesis delta

The new quarterly data reveals superior CTV growth and margin expansion compared to our prior assumptions, indicating strong execution. Our thesis shifts from a neutral stance with uncertainty to a neutral stance with positive operational confirmation. However, we maintain a HOLD rating as valuation concerns and concentration risks persist.