Paying two AI vendors is the leverage. Write it into the contract before it expires

Start with the arithmetic Ramp did not print. Anthropic's 43.5% paid adoption and OpenAI's 39.7% sum to 83.2% of the businesses in the July index ^[1][2], while only 55.7% of that index paid for any AI at all ^[10]. Two vendors cannot cover more of a population than the population contains, so at least 27.5 points of that total has to be the same companies paying both bills, which is about 49% of everyone spending on AI ^[4]. That is a floor derived from the totals, not a survey, and it lands close to the 52% Ramp measured directly in May ^[3].

The value of a floor like that is that it removes the bluff from procurement. A buyer who is already invoiced by two frontier vendors does not have to threaten a migration in order to be believed, and Forbes notes what that buys: pressure on price, data retention, security terms and performance, plus the ability to route different workloads to different models ^[16].

The decay is the part worth budgeting for. Ramp draws the contrast with CRM, ERP and HR systems, where changing vendor means long migrations and painful retraining ^[8], and the same report concedes that enterprise software historically turns sticky once employees are trained, data is connected and workflows are built around it ^[18]. Nothing in the current pattern is load-bearing yet. Anthropic launched Fable 5 on June 9 as its most capable generally available model ^[13] and set the price at $10 per million input tokens and $50 per million output tokens ^[14], with tighter safeguards and a new retention policy attached to its most capable systems ^[15]. Note that output costs five times input at that tier ^[5], and that retention terms arrived as a vendor policy rather than a negotiated clause. Those are precisely the terms that get rewritten when a buyer upgrades tiers, which is when the buyer has least room to argue.

One caution about the evidence. Ramp builds its index from corporate card and invoice payments rather than survey answers ^[11], so it shows who is being billed, not whether a production workload could actually move. Two invoices and one integrated model is a pilot next to a dependency, and it prices like a dependency at renewal.

The switching data suggests how fast the window closes. Ramp found in May that 43% of Anthropic customers had come from another generative AI vendor ^[7], and in 2024 the share of OpenAI customers also using Anthropic went from 3% at the start of the year to 22% by September ^[9]. Those moves happened while very little was wired in. Forbes frames the resulting job accurately: less picking a permanent winner, more deciding which dependencies are worth creating ^[17]. The contract is where that decision gets recorded, or quietly made for you.