Swiss shares closed lower Monday, tracking losses on Wall Street, with a drop for UBS on fresh writedown fears weighing on the index.

UBS AG announced plans for a fresh 15 billion Swiss francs capital hike, fully underwritten by four leading international banks.

The fresh capital injection was triggered by further $19 billion writedowns on US real estate and related structured credit positions, which according to the Swiss banking giant will result in a first quarter net loss of approximately 12 billion francs.

UBS last capital hike over 13 billion Swiss francs had only been approved by shareholders on Feb 27, 2008.

The new subprime hit brings UBS' total writedowns to more than 40 bln usd.

In parallel, UBS announced that chairman Marcel Ospel will not seek re-election as chairman at the bank's April 23 AGM and will be succeeded by Peter Kurer.

Ospel had only recently said that he would seek a further one-year term in office.

UBS said that in the first quarter it managed to substantially reduce its real estate related positions through both valuation adjustment and significant disposals.

It also announced the formation of a new unit to hold certain currently illiquid US real estate assets.

'We believe this capital increase and the creation of a vehicle to separate problem assets from the remainder of our business will allow us to return to sustainable value creation over time,' chief executive Marcel Ospel said.