Cellnex’s CEO Tobias Martinez will leave the top job this summer, in line with a radical new strategy by Europe’s leading pure-play tower operator. Cellnex will reduce its reliance on expansion by acquisition of other towercos or site portfolios, as its aggressive M&A-driven growth of the past few years will inevitably slow because of regulatory scrutiny, and the law of diminishing returns – the biggest and most attractive deals will have been done and the remaining prospects will be smaller and potentially harder to justify in terms of new business versus rising debt. The change in Cellnex’s strategy is not peculiar to that company, or to Europe. Tower operators in some parts of the world are feeling pressure from the…