The Boston Globe has a must-read profile of R. Bradford Malt, the Boston lawyer who is the trustee responsible for overseeing and ministering Mitt Romney’s extensive fortune.

Buried in the profile is, I think, the most illuminating explanation yet of the management of Romney’s politically-dicey holdings, including that now-infamous Swiss bank account:

In 2007, as Romney prepared his first run for president, Malt sold stock in dozens of potentially controversial companies, including casino operators, tobacco growers, and firms with ties to Iran. Last year, after Romney pushed for tougher trade sanctions against China, Malt dumped a number of Chinese holdings. He recently shed a money market mutual fund that had invested in government-backed mortgage companies, Fannie Mae and Freddie Mac, which are blamed for exacerbating the housing bust.

In early 2010, as Romney advanced toward a second presidential campaign, Malt decided to close the $3 million UBS account he set up in Switzerland seven years earlier, realizing it could become a political issue. In 2009, the US government sued UBS to obtain the names of thousands of Americans who secretly held billions of dollars in Swiss accounts.

Malt said he opened the Swiss account not to hide assets, but to diversify Romney’s investments into foreign currencies. If the value of the dollar declined, for example, a rise in the Swiss franc might offset it. The account, Malt stressed, was listed on Romney’s 2010 tax return and Romney paid taxes on the interest, just as he pays taxes on all the earnings from other foreign investments.

Putting aside the question of whether Romney gained any tax advantage from his overseas holdings — many tax experts seem to think there’s no reason to doubt the Romney campaign’s claim that he didn’t — this may be the most extensive explanation yet we’ve gotten for the Swiss bank account. And it is perhaps the clearest look yet at just how carefully Romney’s extensive and controversial holdings — overseas and otherwise — had to be managed to protect his political ambitions.