MILAN, Dec 28 (Reuters) - Shares in Alerion (ARN.MI) hit a record high on Tuesday, rising as much as 5.6%, as the controlling family prepares to look for an investor in the Italian renewable energy firm. The decision mirrors a similar move by Falck Renewables (FKR.MI) earlier this year, whose top investor the Falck family agreed to sell its controlling stake to a JPMorgan-advised (JPM.N) infrastructure fund for 1.5 billion euros ($1.7 billion). read more Daily Il Sole 24 Ore reported on Tuesday adviser Rothschild had already contacted potential investors in Alerion and would intensify its search from January. A person familiar with the process confirmed Rothschild would kick off the search next month. It was not immediately possible to reach Alerion for comment. Italy"s Gostner family could sell up to 49% of a new vehicle holding its 88% stake in Alerion, equivalent to 43% of the listed group, Il Sole said. Based on the company"s current market value of 1.5 billion euros, a 43% stake would be worth 647 million euros. Alerion said in November it would look for a partner, either industrial or financial, to help it fund investments in coming years - and shelved plans for a capital increase. A Milan-based trader said the share gains were driven by speculation that the stake sale would then trigger a mandatory buyout on the remaining shares, as happened with Falck Renewables. Alerion shares were among the top gainers on Milan"s all-share index (.FTITLMS), up 5.1% by 1220 GMT. They have gained 180% since the beginning of this year, supported by strong investor interest in the renewable energy sector which is set to benefit from post-pandemic European Union recovery funds. ($1 = 0.8826 euros)