The LJB and the LMB formally merged in 1958 to form the Oberaargau-Jura Railways (Oberaargau-Jura-Bahnen; OJB).

The cooperation was put on a new footing on 5 April 1984 as a contractual agreement for a joint operation under the name Oberaargau-Solothurn-Seeland-Transport (OSST) between OJB, SNB, BTI, the Oberaargauische Automobilkurse (OAK), the Ligerz-Tessenberg-Bahn (a funicular railway; LTB) and the Bielersee-Schifffahrts-Gesellschaft (Lake Biel Ferry Company; BSG).

OSST, which was formed on a contractual basis, became the de facto predecessor of the company legally merged under the name Aare Seeland mobil AG (asm).

In 1999, RVO, SNB, BTI and OAK merged retroactively into a single public company, usually called Aare Seeland mobil (asm), with effect from 1 January 1999.

A further capital increase became effective on 2 July 2003 with entry into the commercial register, under which the Ligerz-Tessenberg-Bahn AG (LTB) in Ligerz was retroactively taken over by asm on 1 January.

From December 2008, a Niederbipp-Oensingen bus route was also operated that was intended as a trial for the extension of the metre-gauge railway to Oensingen.

The original funicular railway opened in 1912 was replaced by new system due to its age and it reopened on 17 May 2004 under the name of Vinifuni.