TOKYO (Reuters) – Nissan (OTC:) Motor shares jumped as much as 20.6% on Tuesday after a filing showed an entity related to activist investor Effissimo Capital Management had taken a stake in the struggling Japanese automaker. In a regulatory filing on Monday, Nissan listed Cayman Islands-registered ECM Master Fund as a shareholder with a 2.5%stake as of end-September. ECM Master Fund is affiliated with Effissimo, according to SEC filings. Source