Corporate giants are under attack from small, nimble start-ups overwhelming them with new technologies. Established companies with scale, control over distribution, brand power and millions of customer relationships are no longer seen as obstacles to agile rivals with innovative business models.A survey finds business leaders believe four out of 10 top-ranked companies in their industries worldwide won't survive the next five years. They mention accelerating technology, shifting business models and a need to merge to cut costs to ensure they don't become footnotes in someone else's corporate history."Entire industries are being side-swiped by these effects," said James Macaulay, co-author of the study, which polled 941 business leaders from a dozen industries in the world's 13 biggest economies."Digital disruption now has the potential to overturn incumbents and reshape markets faster than perhaps any force in history," the survey states. The report can be found at http://bit.ly/1IyV1cKThe survey was conducted by Swiss business school IMD, the International Institute for Management Development, with backing from internet equipment maker Cisco, where Macaulay is a consultant.Industries with the highest number of top-rated companies at risk were hospitality/travel, media and entertainment, retail, financial services and consumer goods/manufacturing, in that order, the survey showed. Meanwhile, industries which still largely deliver physical products or services, such as pharmaceuticals, utilities and the oil and gas sectors, were rated least likely to be disrupted. ..