Wall Street
A Wall Street sign is seen outside the New York Stock Exchange on June 9, 2014. Reuters/Carlo Allegri

(Reuters) - U.S. initial public offerings by venture-backed companies fell to a two-year low in the first quarter of 2015, according to data from the National Venture Capital Association and Thomson Reuters.

About 17 venture-backed companies raised $1.43 billion in the three months ended March, compared with 37 that raised $3.40 billion in the same period a year earlier, according to the report.

The last time the number fell below 20 was in the first quarter of 2013, when eight venture-backed companies raised $716.9 million.

Box Inc (BOX.N), an online data storage provider, had the biggest IPO in the latest quarter, raising $201.2 million. It began trading on the New York Stock Exchange on Jan. 22.

Life sciences companies dominated the IPO market, with 13 of the 17 offerings coming from the sector.

The average amount raised was $84.3 million, down from $92 million in the first quarter of 2014.

Among venture-backed mergers and acquisitions, only 16 of the 86 during the quarter reported deal size. The average deal size was $128.1 million, compared with $245.8 million a year earlier.