* New company to list on the Australian stock market * AMP announces A$200 million share buyback * Further cash-backs to investors unlikely - UBS (Recasts and updates throughout with investor, share reaction) SYDNEY, April 23 (Reuters) - Embattled Australian wealth manager AMP Ltd has ended protracted talks to sell its asset management arm’s private markets business to Ares Management Corp, instead announcing on Friday it will spin off and re-brand the unit. The restructure is expected to be completed in the first half of fiscal 2022, and will be followed by a A$200 million ($154 million) share buyback. AMP first disclosed Ares had approached it in late October with an offer to buy the whole company for $4.9 billion. It downgraded that in February to a proposal to take a majority stake in AMP Capital’s private business.