* Analysts expect Zachert to tackle overcapacity
* Lanxess shares up almost 9 pct, Merck shares down 10 pct
* Zachert had been seen as potential next Merck CEO (Adds analyst, Zachert, Kley comments, updates shares)
FRANKFURT, Jan 27 (Reuters) - Shares in Lanxess rose almost 9 percent on Monday after news the German synthetic rubber specialist had attracted its former finance director back from Merck KGaA to be its CEO, fuelling speculation he may tackle overcapacity.
Shares in drugmaker Merck meanwhile, which have gained 30 percent over the last year, dropped 10 percent following the announcement late on Sunday of the departure of Matthias Zachert, who had been viewed as a potential future CEO.
Zachert, who has been working as finance chief at Merck, will replace Axel Heitmann at the helm of Lanxess, who is leaving after eight years.
Zachert is well regarded by financial markets and investors after helping, alongside Heitmann, to set up Lanxess following its spin-off from Bayer and for playing a key role in restructuring Merck.
Lanxess, the world's largest maker of synthetic rubber for tyres, door sealants and windscreen wipers, is in the midst of an overhaul including job cuts and potential asset sales. But it is also looking into takeovers in the medium term to ease its dependence on the automobile sector.
Zachert was given a warm welcome by analysts covering Lanxess, with some hoping that he would rein in investment.
A shift from upgrading existing plants to building new ones, had created overcapacity over the past two to three years, Bank of America Merrill Lynch analysts said in a research note.
"Zachert may well have something close to a 'carte blanche' in terms of implementing change," they said, upgrading the stock to 'buy' from 'neutral'.
UBS analysts lauded Zachert as "extremely fit" to prudently allocate capital.
"Biggest change to expect is capex policy - somewhat out of tilt as of late," they said.
In a call with journalists, Zachert said had been drawn by the chance to fix what he described as a state of disarray at Lanxess.
"It was indeed the attachment to the old company and also the realisation that not everything was in order ... people used to stand like one man behind the company and things are obviously not going in that direction any more."
While Merck boss Karl-Ludwig Kley said on the call that Zachert would have been a serious contender to succeed him, he signalled he had no plans to make way.
He said his contract runs until September 2016 and that at the age of 62 he was well shy of the official age limit of 75 for his role at Merck.
"I enjoy my job," he said. (Reporting by Ludwig Burger, Frank Siebelt; Additional reporting by Victoria Bryan and Daniela Pegna; Editing by Mark Potter)