From Jan. 1 to May 28, M&A activity reached $746.9 billion in estimated value, up 52% from a year earlier, according to data compiled by Thomson Reuters. By dollar amount, it’s the strongest year-to-date period for U.S. dealmaking since Thomson Reuters began recording deals in 1980.

Some historic pending transactions have juiced the total dollars so far. The Charter-Time Warner Cable arrangement is the largest cable television deal on record, while the $36.2 billion Avago Technologies (NASDAQ:AVGO) bid for Broadcom (NASDAQ:BRCM) is the second-largest tech deal on record.

Health care, technology and media account for 53% of U.S. M&A value so far this year, compared to 49% in the year-ago period. Cable M&A totaled $97.2 billion so far this year, up 42% from a year earlier.

It merits mentioning that merely announcing a deal doesn’t mean that shareholders and regulators will necessarily approve it. Comcast (NASDAQ:CMCSA) abandoned its $45.2 billion bid for Time Warner Cable last month after federal regulators raised too many hurdles over anti-competitive elements in the proposed transaction.

Among the investment advisors racking up fees for counseling buyers or sellers of U.S. deals, Morgan Stanley (NYSE:MS) — which advised Time Warner Cable on the Charter deal along with Citigroup (NYSE:C), Allen & Co. and Centerview Partners — topped the list of transactions that a single advisor worked on, with 58 deals valued at $209.3 billion.

Global M&A activity totaled $1.7 trillion, up 35% from a year earlier.