By Joshua Kirby

Assicurazioni Generali SpA has launched an all-share tender offer for smaller rival Assicurazioni Cattolica SC after achieving the minimum stake threshold.

The Italian insurer said that as of Friday it had built a stake of more than 66.67% in Cattolica, crossing the threshold needed for a full takeover. Dow Jones Newswires reported Thursday that Generali's stake had reached around 54%.

The takeover, launched last month at a bid of EUR6.75 a share, has a value of around 1.18 billion euros ($1.38 billion). Prior to making the bid, Generali already held a stake of around 24% in Cattolica.

Write to Joshua Kirby at joshua.kirby@wsj.com; @joshualeokirby