Altair Engineering's (NASDAQ:ALTR) $10.6 billion sale to Siemens (OTCPK:SIEGY) may see some regulatory challenges, according to an Oppenheimer analyst.

Siemens (OTCPK:SIEGY) on Wednesday agreed to buy Altair Engineering (ALTR) for $113 a share in cash, or a total deal value of $10.6 billion. Altair (ALTR) makes engineering software for the aerospace, automotive, energy and financial services industries, among others.

The deal is expected to close in the second half of next year, prompting some traders to question why the acquisition will take a seemingly long time to close. Shares of Altair fell 4.3% on Thursday, likely as traders were concerned about the close date and regulatory reviews.

"We expect the deal to encounter some regulatory hurdles given the sensitive nature of simulation workloads," Oppenheimer analyst Ken Wong wrote in a note on Thursday. "Siemens already has an end-to-end design platform (CAD, PLM, Simulation) and is a Top 3 EDA vendor."

The Altair (ALTR) said may also have to be reviewed by China's antitrust regulator, Wong added.

"... as we saw with ANSYS, China's SAMR could still require formal approval due to the sensitive impacting key industries (tech, auto) nature of simulation and EDA workloads," Wong wrote.