When Mitt Romney was running for president, he mentioned putting his wealth in a blind trust. Is this required when a wealthy person becomes president?
In general, by law, there's no requirements around the president's financial situation.
Having said that, there was a very good reason for Romney to consider the blind trust:
There are very stringent requirements around corruption and conflict of interest. I don't recall this ever being tried on a President but senators and governors were prosecuted for corruption.
Leaving aside legal angle, it definitely would cost a wealthy president a ton of political capital to be accused of doing things that enrich himself. Doesn't even matter if the accusations are accurate - that never stopped a good smear campaign from sticking.
If Romney has no idea how he's invested, he can't be accused of doing things to benefit his finances, either by law or by political opponents (or mass media members, but I repeat myself). So it was a great pre-emptive move on his part to defend against either possibility of damage.
Theoretically, Romney may have had other possible concerns on legal/regulatory front that warranted a blind trust, because he worked in a financial industry in an investment firm. The industry is regulated even more than others, both in terms of corruption and conflict of interest.