The Galaxy Note 10.1 turned out popular enough to warrant this move
Styluses aren't exactly widespread on the consumer electronics market, as people usually use their fingers to navigate touchscreens.Samsung's Galaxy Note 10.1 proved very popular though, and the S-Pen Stylus is one of its primary features.
In order to have an easier time striking deals for styluses, Samsung has bought a stake in Wacom.
Wacom actually has 85% of the global “electronic pen” market, many of which are used by smartphones and tablets.
And since sales of such gadgets have doubled between 2011 and 2012, Samsung doesn't have anything to lose by acquiring a share of Wacom, but quite a bit to gain.
Meanwhile, Wacom will get $58.9 million / 43.46 million Euro to invest in "product development and manufacturing and supply system enhancements for products to be supplied to Samsung Electronics."