The Spanish investment firm Asterion Industrial Partners has written off the entire value of its investment in the Irish company X3T Broadband. X3T was spun out of National Broadband Ireland (NBI) to commercialise technology enabling telecoms operators to share access to similar networks around the world. Asterion is the largest shareholder in both NBI, the group of companies contracted to roll out Ireland’s subsidised National Broadband Plan, and X3T. NBI and X3T are chaired by Irish-American entrepreneur David McCourt, a minority investor in both businesses. Asterion’s impairment of X3T does not affect the National Broadband Plan nor NBI, where Asterion…