Shares in Quindell jumped more than eight per cent to 74.25p in mid-afternoon trading, after Morgan Stanley increased its stake to more than five per cent.
Shares in the insurance claims processor lost more than 90 per cent of their value last year, after the company was accused of having "magical... paper profits" by mysterious US-based short seller Gotham City Research.
After a series of catastrophes, the year culminated in the departure of founder and chairman Rob Terry.
But shares have jumped since the beginning of January, when it announced it had appointed Richard Rose and Jim Sutcliffe as chairman and deputy chairman.
Although the appointment came with its own problems - Sutcliffe was forced to step down as chairman of the Financial Reporting Council's codes and standards committee after it emerged the pair had been granted more than £25m in stock options, which contradicts the UK's corporate governance code - investors have largely welcomed the move.
However, shares tanked 20 per cent earlier this month when law firm Slater & Gordon insisted it was still in talks to buy its legal arm.