Nebius's $5B convertible: the 0.50% coupon is a teaser, the all-in cost is 19% of revenue

AI infrastructure capital now borrows like 2007 mortgage teaser rates: a low headline number that hides the real bill in conversion premiums (the upfront charge a bondholder receives if they convert to stock at a price above today's share price), principal accretion (the principal owed grows over the life of the note), and dilution optionality (the company's choice to settle in cash, shares, or a mix). The spread between coupon and all-in cost is the actual price of scaling an AI cloud in this cycle. This interpretation applies to the Nebius deal specifically; whether it is representative of broader AI infrastructure capital costs in this cycle requires additional deal-specific evidence.

Nebius's $5.0B convertible, dissected in the Motley Fool's analysis, is the cleanest exhibit of that gap. The company priced $3B of 2030 notes at 0.50% and $2B of 2034 notes at 4.50%, and the wires dutifully quoted those coupons. Add 110% principal accretion on the short tranche and 125% on the long one, layer in conversion strikes at $313.46 and $324.65 (roughly 40% and 45% above the $223.90 close), and the optional $750M greenshoe, and the math puts the effective annual cost near $258M. That is about 19% of the $1.36B trailing revenue base, not the roughly 8% the coupons alone imply.

The mechanism travels: read a convertible headline by coupon, and you will underestimate the cost by a factor of two or more. The Fool's number is just where the math is most visible. About 15.7M new Class A shares sit behind conversion, and Nebius can settle in cash, shares, or mix. Read the optionality, not the coupon.