Billionaire investor and corporate activist Carl Icahn is once again making his presence felt at US handset vendor Motorola, after buying up enough stock to become the company’s biggest shareholder.

According to an SEC filing released Wednesday, Icahn boosted his stake to 9.99 per cent, making him the biggest single shareholder. The move comes as Icahn, a long term campaigner of Motorola’s break up, gets his wish.

The company has recently sold its network equipment division to Nokia Siemens Networks, and will split its handset and set top box and enterprise and iDEN units out into two separate divisions.

Earlier this week the company announced the return of Daniel M. Moloney as president of the Mobility business, returning from a short stint as CEO of electronic component manufacturing firm Technitrol. Previously, he was executive vice president at Motorola and president of Motorola’s Home and Networks Mobility business.

Keeping up momentum after its success with the Android platform, Motorola is also rumoured to be working on an Android-based tablet device for US carrier Verizon Wireless. Verizon CEO, Lowell McAdam recently said that Verizon is working with the Google-backed operating system to see what it could do to really lift the internet tablet experience. Now it looks like Motorola is in the picture as the device manufacturer, using its position as the vendor of Verizon’s FiOS set top boxes to integrate TV services into the device. This would be something of a unique selling point in the tablet market.