Mammoth IPOs by the Brazilian unit of Spanish bank Banco Santander and U.S. risk specialist Verisk Analytics Inc raised nearly $10 billion on Tuesday, almost twice the amount raised by U.S.-listed IPOs in 2009.

Banco Santander (Brasil) SA raised $8.05 billion, after selling 600 million units for 23.5 reais each, within the estimated range.

The bank had filed to sell 525 million units, with each unit representing 55 common shares and 50 preferred shares, but the offering was increased by 75 million units to meet demand from investors.

The IPO was the largest ever for a Brazilian company, beating the offering by credit card processor VisaNet in June. It also surpassed the IPO by China State Construction Engineering Corp, which raised $7.3 billion in July, to become the biggest worldwide in 2009.

Verisk raised $1.88 billion in its IPO, after pricing shares at a higher-than-expected $22 each in the largest new offering by a U.S. company since Visa Inc's $19.6 billion IPO in March of 2008.

Prior to these IPOs, total U.S. proceeds stood at $6.33 billion from 31 deals in 2009, according to Thomson Reuters data, which includes IPOs by real estate investment trusts.

Verisk, which does most of its business through its subsidiary ISO and is owned by a group of insurance companies, collects actuarial and underwriting data related to U.S. property and casualty insurance risks.

All 85.25 million shares in the IPO were being sold by Verisk's existing shareholders, which include American International Group Inc, Hartford Financial Services Group and ACE Group Holdings.

The recent resurgence of the U.S. IPO market stands in contrast to the earlier part of 2009, when falling stock markets made IPOs difficult to complete; there was only one IPO in the first three months of the year in the United States.

But recovering markets have drawn an increasing number of larger IPOs in recent months. The Verisk and Santander Brasil IPOs bring to three the number of $1 billion IPOs in the United States in the past two weeks alone, along with Chinese video games maker Shanda Games Ltd.

Both new stocks will begin trading on Wednesday -- Banco Santander (Brasil) on the New York Stock Exchange and Sao Paulo, and Verisk on the Nasdaq.

(Reporting by Phil Wahba; Editing Bernard Orr)