TIMELINE - UBS appoints ex-Credit Suisse head as CEO

(Reuters) - Stricken Swiss bank UBS appointed Oswald Gruebel, a former head of rival Credit Suisse, as its new chief executive on Thursday, replacing Marcel Rohner.

Following are key events in the subprime mortgage-related crisis and ensuing economic downturn that have impacted UBS:

* CLOSES DILLON READ HEDGE FUND UNIT - MAY 3, 2007

UBS shocks investors by closing its Dillon Read hedge fund unit after posting lower-than-expected first-quarter earnings, then a rare event from a bank whose track record had earned it a reputation as a serial outperformer.

* WRITEDOWNS TO CAUSE THIRD-QUARTER LOSS - OCT 1, 2007

UBS warns a 4 billion Swiss franc (2.4 billion pound) subprime hit would cause a third-quarter pretax loss. A few weeks later, UBS reports a quarterly loss of 726 million Swiss francs, its first quarterly loss in nine years.

* MORE WRITEDOWNS - JAN 30, 2008

UBS announces another writedown, this time for $4 billion (2.8 billion pound). Two weeks later, it posts a full-year loss of 4.4 billion Swiss francs. Shareholders back an $11.9 billion capital injection from Singapore and an unidentified Middle East investor.

* WRITEDOWNS DOUBLE, DUMPS CHAIRMAN OSPEL - APRIL 1, 2008