MADRID (Reuters) -U.S. buyout firm Apollo made a cash bid for Applus Services on Friday which values the Spanish industrial testing company at 1.23 billion euros ($1.33 billion).

Apollo said in a filing to Spain’s stock market regulator that it had offered 9.50 euros in cash per Applus share, a 1.9% premium over Thursday’s closing price of 9.32 euros.

Applus shares have gained 45% so far this year on speculation several investors were preparing a takeover.

The regulator had earlier suspended trading in Applus shares, before Apollo announced its bid, and its shares jumped 6.3% to 9.85 euros when the suspension was lifted, suggesting expectations of a possible higher bid or counter offer.

Last week, infrastructure private equity fund I Squared Capital Advisors said it was evaluating a takeover bid for Applus together with TDR Capital.

Reuters reported last month that funds including Apollo, Apax, I Squared Capital Advisors and TDR were looking at Applus.

The Applus board reacted positively to Apollo’s bid for 100% of its shares, saying in a statement that it showed confidence in the company’s performance and gave shareholders an option to monetize their investment at a premium.

Santander, BNP Paribas and law firm L&W are advising Apollo.

($1 = 0.9223 euros)

(Reporting by Inti Landauro and Jesus Aguado, editing by Andrei Khalip and Alexander Smith)