There’s really not enough information in that article.
Though there are some types of loans that would only go up about $70 per month if they reset now, those same loans would only have gone up about $70 if they reset in December. The type of loans that would have reset by $450 in December will still reset by about $450. The mortgage interest rates have hardly changed. They were down at the beginning of the year, but are back up now. Some mortgage rates are even higher than they were in December
Even the next paragraph in that article says “others still face a rate shock because they had an artificially low introductory rate”
Those loans that are going up by several percentage points are doing so because they started out with the “teaser” rates that the article mentions. You are correct that the interest rate on ARMs continue to fluctuate even after the introductory period, generally this is annually. The interest rate changes after the introductory period will not be as great. Usually there is a cap on how much the difference can be from one year to the next regardless of what the prime rate does.
So basically if the borrower can survive the initial large jump, then it is likely that they can survive the smaller increases (or decreases) that come in the future.
