UPDATE 2-Expected bid for motorway unit lifts shares in Italy's Atlantia

* CDP consortium to file 8.5-9.5 bln euro offer by Feb. 24

* Motorway sector under the spotlight after ASTM buyout offer

* Shares in ASTM up 27% on Monday (Adds TCI comment, ASTM buyout offer)

MILAN, Feb 22 (Reuters) - Shares in Italy’s Atlantia rose more than 3% on Monday, boosted by expectations the infrastructure group would receive a binding offer for its 88% stake in motorway unit Autostrade per l’Italia this week.

In addition, a buyout offer on smaller motorway operator ASTM sent the stock up nearly 30%, putting the transportation sector under the spotlight.

A consortium comprising Italian state lender CDP and investment funds Macquarie and Blackstone will file a proposal to buy Atlantia’s stake in Autostrade by Wednesday, several sources close to the matter said.

The proposal values the whole of Autostrade at 8.5 billion-9.5 billion euros ($10.3 billion-$11.5 billion), the sources said.

According to daily La Stampa, the board of CDP will give its green light to the bid on Monday and the valuation of the unit will be in the upper part of the 8.5 billion-9.5 billion euro range.

CDP’s move is part of an effort to end a political dispute over Autostrade, which has been under the crosshairs since the deadly collapse in 2018 of a motorway bridge in Genoa.

Atlantia, which is controlled by the powerful Benetton family, will review the bid on Friday.

It is not clear whether such an offer could be accepted by Atlantia after the group’s board rejected a similar bid last year and several minority investors said that the 8.5-9.5 billion euro valuation was too low.

Among them is hedge fund TCI, which on Monday said that a 1.7 billion euro buyout offer announced by ASTM’s top investor to take the company private was relevant for Autostrade.

“The valuation implied by the bid on ASTM more than underpins our 11-12 billion euro valuation for Atlantia’s 88% stake in Autostrade,” Jonathan Amouyal, Partner at TCI Advisory Services, told Reuters.

“It also shows that with no unlawful decree, there is appetite for infrastructure investments in Italy,” he added, citing the dispute with Rome over a law that had made the revocation of Autostrade’s concession easier for the government. ($1 = 0.8259 euros) (Reporting by Francesca Landini and Stephen Jewkes; Editing by Susan Fenton and Nick Macfie)