EU regulators restarted an antitrust investigation on Tuesday into Sony Corp. and Bertelsmann AG's 2004 deal to combine their music units, setting a new approval deadline of Oct. 10.
The European Commission suspended on its inquiry in March, saying the companies had not submitted the information needed to examine the deal.
It did not explain why it restarted its probe.
Regulators are examining the deal that formed the world's second-largest record label after an EU court overturned earlier clearance to go forward, saying the Commission had not done enough to prove that there was no monopoly in the record industry.
The Sony-BMG merger brought Sony artists like Aerosmith, George Michael and Barbra Streisand and BMG's Avril Lavigne and Elvis Presley under one label, and shrank the number of major music companies from five to four.
The EU's executive arm is now reconsidering the deal under current market conditions, taking into account developments such as growing sales of online music.
If the EU clears the deal again, there is a legal precedent to demand selloffs or changes to business behavior to counter antitrust concerns.