This article was updated Jan. 24 to include just-released tax information.

Mitt Romney's presidential campaign has an increasingly difficult problem: People can't stop talking about his money -- how he made it, how he spends it, where he stashes it and how he invests it.

As much as Romney tries to divert attention from Bain Capital, the private equity firm he co-founded in 1984, questions remain about the way Bain handled company restructurings and layoffs.

People also want to know why he wouldn't release his tax returns early on, why his tax rates are so low and why some of his money is parked in the Cayman Islands. He did release two years of tax information late on Monday, Jan. 23, showing $42.5 million in income for 2010 and 2011, mostly from gains on investments, the Associated Press reports.

Romney lost the South Carolina primary contest last weekend, grabbing only 28% of the vote compared with the 40% that went to winner Newt Gingrich. His performance was clearly hurt by a less-than-stellar debate performance and mounting questions about his finances.

So Romney finds himself in an absurd paradox. He hoped to win American hearts as the savvy businessman who could turn the economy around. Instead, his business experience is almost a liability as his campaign faces deep-rooted antagonism toward Wall Street and the richest 1%.

The former Massachusetts governor grew up in a wealthy family, but he really brought in the big bucks after co-founding Bain. Now, he and his wife have a fortune that his campaign estimates is between $190 million and $250 million.

Amid all the questions, here's a look at what we do know about what he earns -- and how he invests his fortune.

A diverse portfolio

Romney probably has much more money than anyone else running for president. And the financial disclosure documents (.pdf file) he filed last year as a presidential candidate show a vast array of investments. This man takes diversification seriously. His wife even owns horses valued at as much as $500,000 through a limited-liability company. He owns as much as $500,000 in gold.

(Dollar amounts on the form are reported in wide ranges, from $250,001 to $500,000, for example, and from $1 million to $5 million.)

Romney's assets are mostly held in some 160 funds managed by several investment firms, including Goldman Sachs and Thornburg Investment Management. Romney has wisely put nearly all of his assets in blind trusts and individual retirement accounts in his and his wife's names. In each case, a trustee or a third-party investment manager has complete investment discretion over the assets.

Romney's portfolio is unusual in many aspects, including this one: His individual retirement account has between $20.7 million and $101.6 million in it. But IRA gains are tax-deferred, and The Wall Street Journal reported that Romney likely contributed pretax dollars to the account. That means Romney has been able to defer paying taxes on much of his wealth -- at least until he withdraws the money.

It's very rare to have more than $100 million in an IRA, the Journal report said.

Mitt Romney © John Moore, Getty Images

You'd be hard-pressed to find any stocks that Romney or his investment managers appear to favor. It doesn't really look as if his portfolio is hot on individual stocks, with the exception of Ford Motor (F, news). Romney's trust owns between $250,000 and $500,000 worth of Ford shares.

Romney's portfolio is instead filled with other types of investments, including exchange-traded funds, bonds and mutual funds. For example, he has between $1 million and $5 million in the iShares MSCI EAFE Index (EFA), an ETF that tracks stocks in developed markets outside the U.S.

He also has tens of millions of dollars in Federal Home Loan Bank bonds with a wide range of maturity dates.

He has between $1 million and $5 million in the SPDR S&P 500 (SPY, news), an ETF that tries to replicate the performance of the Standard & Poor's 500 Index ($INX).

Plain-vanilla investments

You get the sense that Romney's portfolio has been carefully engineered to be as noncontroversial as possible -- exactly what you would expect from someone who is smart, incredibly wealthy and making his second run for the presidency.

In fact, it doesn't seem as if these investments were chosen primarily for their profit potential. Rather, it appears his money managers have stashed his assets in the blandest and least-offensive places possible to wait out the election. That takes skill in and of itself.

Given his wealth, he may be aiming his investments at preserving capital rather than growing it. Still, he recorded $42.5 million in income over two years, most of it capital gains -- gains on investments.

His financial disclosures, though, suggest Romney's fortunes didn't increase much in the four years between campaigns. His campaign estimates the range of his assets at between $190 million and $250 million -- exactly the same range the last time he ran for president, The New York Times reported.

Continued on the next page. Funds mentioned in this article include Goldman Sachs Small Cap Value A (GSSMX), Goldman Sachs Strategic Income A (GSZAX)and Goldman Sachs Local Emerging Markets Debt Fund A (GAMDX).