The European Union regulators have initiated a thorough investigation of the $7.4-billion acquisition of Sun Microsystems by software major Oracle.
The European Competition Commission investigation must be completed by 19 January 2010.
"The Commission has to examine very carefully the effects on competition in Europe when the world's leading proprietary database company proposes to take over the world's leading open-source database company," EU commissioner Neelie Kroes said.
The US Department of Justice (DoJ) had given its approval to the deal in late August (See: Oracle's acquisition of Sun approved by US justice dept).
The European Commision, which is known to take a tough stance on market dominance and anti-competition activities, will now look closely at Sun's Java networking software franchise and database software.
Regulators in the US questioned Oracle's market power in some areas of its business, but raised fewer concerns than the Europeans about open-source software.