Five IBM engineers left to build the software IBM refused to build — and outgrew IBM

Every large company has a SAP in its history: the project killed because it threatened existing revenue, and the team that left to build it anyway. The question is whether the company can tolerate cannibalising its own cash cow.

In the early 1970s, a team of IBM engineers in Mannheim developed a prototype for real-time enterprise software — a system that could process business transactions (accounting, payroll, inventory) as they happened, rather than in overnight batch runs. IBM's management decided the product was not a priority. The mainframe business was profitable; the new software was a distraction.

In 1972, five of the engineers — Dietmar Hopp, Hasso Plattner, Claus Wellenreuther, Klaus Tschira, and Hans-Werner Hector — left IBM and founded SAP (Systemanalyse und Programmentwicklung) in a small office in Mannheim. They pooled their savings. Their first client was a chemical company that needed real-time accounting. The software they built became SAP R/2, then R/3, then the enterprise resource planning (ERP) standard that runs most of the world's large companies.

The story is told in interviews and in Hasso Plattner's occasional public remarks: the decision to leave IBM was not a rebellion but a calculation. IBM had the idea, the engineers, and the customers. What IBM did not have was the willingness to cannibalise its own batch-processing revenue. The five founders had nothing to cannibalise, so they built the thing IBM would not.

The five founders left IBM and built the software themselves, creating a €300B+ market that outgrew IBM.

IBM's batch-processing business was profitable. Real-time software would have made it obsolete. The decision to say no was rational for the existing business — and fatal for the next one

The five founders had domain expertise and customer relationships from IBM. What they lacked was capital, brand, and distribution — all of which they built from the revenue of the first product

The German industrial base — chemical, automotive, engineering — was the perfect first market: large companies with complex processes and no existing software. SAP grew with its customers

The most dangerous competitor is the one you trained. IBM's engineers built SAP with IBM's knowledge and customer list. IBM did not give them permission — permission was the one thing not needed.

SAP is now the world's largest enterprise software company, with a market capitalisation exceeding IBM's. All five founders became billionaires. Hasso Plattner remains SAP's chairman. IBM's enterprise software business, built decades later, has never matched SAP's market share in ERP.