China was the fourth-largest deal maker in the United States over the past year, up from sixth at the same stage in 2014, according to a new cross-border merger-and-acquisition index launched by the US law firm Baker & McKenzie.

During the first three quarters of this year, the US accounted for the highest number of M&As by Chinese mainland buyers－46 deals worth $13.57 billion.

Hong Kong was the second most popular target market in terms of value, worth a total $12.46 billion, followed by Italy ($8.97 billion), Ireland ($7.34 billion), Bermuda ($4.07 billion), Switzerland ($4.023 billion), and Australia ($2.87 billion).

In terms of the number of transactions, the top 10 destinations for Chinese mainland companies were, in order, Hong Kong, the US, the United Kingdom, Germany, Australia, Canada, Singapore, Taiwan, India and Israel.

During the same period of 2014, Chinese mainland companies made 32 cross-border transactions valued at $7.61 billion in the US.

Based on turnover, the most popular target sectors in the US by Chinese mainland buyers were semiconductors, hardware and software, automobiles, leisure and travel, energy resources, Internet and e-commerce, industrial product and service.

With 1,400 partners in 47 countries, Baker & McKenzie said its study showed Chinese mainland companies completed 221 cross-border deals in the first three quarters of 2015, with transactions worth $70.72 billion. Those compared with $44.80 billion from 149 deals in 2014.

The biggest deals this year include Tsinghua Unisplendour Corporation Ltd's $3.8 billion bid for a 15 percent stake in Western Digital Corporation, which, if approved, would become the single largest Chinese investment in a US company to date.

Buyers from the Asia Pacific region have been particularly active in the US market this year. Japan was the third-biggest buyer of US targets, with 53 deals totaling $29.5 billion.

"US companies are looking for access to customers, industries and new markets, particularly as they aim to compete in highly dynamic industries," said Matthew Gemello, Baker &McKenzie's M&A partner.

He said the relatively strong dollar makes acquisitions economically more feasible, and there is optimism in the US economy, which is making deal-making more attractive even in industries where overseas companies traditionally have been more risk-averse.