MGIC Investment Corp (MTG) to Become More Conservative

I just read an article about MGIC Investment Corp (MTG), the biggest mortgage insurer. This was published last Friday, December 7th:

But MGIC, going forward, will no longer insure loans for borrowers with credit scores below 575.

The insurer also is putting in some geographic restrictions in places like California and Florida -- two areas hard-hit by the mortgage crisis. MGIC will insure loans up to 95 percent of a home's value, meaning they won't insure homes with no equity...

Another change will limit the insurance MGIC offers people who have Alt-A loans, which generally require only limited verification of income.

So, if they aren't insuring those types of loans starting now, can I infer that they were insuring them up until this week?

And, if so, what were they thinking?

Disclosure: Author owns MTG puts.