If precedent serves, NTT DoCoMo’s $2.7bn swoop on India’s sixth biggest wireless carrier will end in tears. At the turn of the century, the overseas misadventures of Japan’s biggest mobile operator destroyed some $9bn of value. Recent Japanese shopping in India has been equally misjudged. Daiichi Sankyo recently paid $4.2bn for a controlling stake in Ranbaxy Laboratories, India’s biggest drugmaker by sales. That allowed the Indian owners to cash out big time – its shares are now worth less than a third of the price the Japanese paid – and exit before the US regulator slapped a sales ban on 30 products.

Of course, precedent is a fickle barometer. In recent years, DoCoMo has concentrated on acquiring minority stakes in emerging market carriers. It has more than $5bn cash on its balance sheet and the yen buys more rupees than it did. Still, that does not justify blowing $2.7bn for a quarter of an unquoted entity whose main holding is listed Tata Teleservices (Maharashtra). On a back-of-the envelope basis, using the listed entity’s net debt, that gives an enterprise value per subscriber of $370. That is less than half what Vodafone paid for control of Hutchison Essar, a superior firm, but nearly three times the level of India’s more comparable Idea Cellular.