<p>Of all the demands that activist hedge funds make, one has emerged as a clear favorite over the past year: asking the management of a company they target to put up the "for sale" sign.</p>
<p>Heady valuations have made the windfall from a sale too hard to resist for dissident shareholders, turning what used to be a fall-back option in past campaigns into preferred strategy, and prompting a slew of takeovers in the process.</p>