Mergers and acquisition deals announced so far this year have topped $3 trillion, the highest since 2007, helped by mega deals in the healthcare, energy and power sectors.

The total value of deals globally jumped about 48 percent to $3.06 trillion as of Nov. 20, compared with the same period last year, according to Thomson Reuters data.

Goldman Sachs Group Inc (GS.N) retained its No. 1 position as M&A adviser with deals worth $877 billion, followed byJPMorgan Chase & Co (JPM.N) with $651 billion and Citigroup Inc (C.N) with $633 billion.

Morgan Stanley (MS.N) slipped to the fifth position from third last year.

The M&A market, which was the doldrums following the financial crisis, got a lift from a resurgent stock market and growing confidence among cash-rich companies.

The $66.4 billion bid for Allergan Inc (AGN.N) by Actavis PLC (ACT.N) this week more than doubled the total value of deals in the healthcare sector to $364 billion.

Halliburton Co's (HAL.N) plans to buy smaller rival Baker Hughes Inc (BHI.N) for about $38.5 billion raised the value of deals in the energy sector by 68 percent to $516.3 billion.

Other notable deals include Comcast Corp's (CMCSA.O) $45.2 billion bid for rival Time Warner Cable Inc (TWC.N).

The United States led the way with about $1.41 trillion worth of deals, up 58 percent compared with last year.