Activist investors are back. A whole new generation of cage-rattlers are taking on some of the world's biggest corporations - and some of the original activists of the 1980s have returned to the fray with a bang.
The founders of Cevian Capital - Europe's largest activist fund - are generally happy to stay under the radar and prefer a collaborative approach rather than the aggression typical of some other activist investors.
(Slideshow: Who are the Top 10 cage rattlers?)
Their recent investment in German steelmaker ThyssenKrupp, which is struggling after attempts to expand in the U.S. and may need to raise capital later this year, is a case in point.
But sometimes, other investors complain that activist shareholders don't act on behalf of all shareholders.
Do activist shareholders add value?