COPENHAGEN—Wind turbine maker Vestas on Monday said the cyber attack it reported at the weekend has affected parts of its internal IT infrastructure and that data has been “compromised.” The incident, the financial implications of which are as yet unclear, comes as Vestas juggles with record demand for green power against supply constraints and high raw material costs that are pressuring profit margins. Shares in the world’s biggest manufacturer of wind turbines, already down 25 percent this year before the cyber attack, dropped by about 3 percent in early trade on Monday. In addition to concerns over the nature of any data breach, near-term market focus will also be on production delays and related costs, including the cost of resolving the issue, Citi analysts said in a research note. The cyber security incident on Nov. 19 forced Vestas to shut down IT systems across multiple business units and locations to …