. >> reporter: california analysts mark hanson says roughly 70% of may sales for the builders are suspect. he points to the numbers, of the sales contracts signed in may 31% were for completed homes so buyers would have locked in mortgage rates near record lows, no problem. 24% were for homes under construction so some locked in a rate if the home was almost done, but some did not and 36% of the sales contracts signed in may were for homes that were not yet started. those buyers in most cases did not lock in rates and are already facing sticker shock at today's level. that could mean cancellations. >> it will be depending on the type of home builder that you're looking at. if you're looking at the coal brothers, a luxury builder, those customers can afford a rate rise and still be able to close their home or buy a home. so it's going to be very dependent on the significaegmen housing market. >> reporter: analysts for the big public builders say they are watching it closely and some do expect cancellations to climb. the jump in rate since the beginning of may pushed the average barrowers p

now, analyst mark hanson, who pointed me to these numbers, says he believes that at least 70% of alligher risk a.r.m. he says in order to save the deals. some of the builders we've spoken to say in just the last two weeks they've had a lot of calls from customers concerned about locking in rates. >> the challenge for a loan lock for a home that's under construction is they never know when they're going to actually have their closing dates. the cost of doing a loan lock up to nine months runs 2.5 points and a lock for a three months is a half point. and so people are trying to judge on whether they want to invest in that loan lock. >> now, those loan locks may be so expensive they could price some customers out of the deal. analysts for home builders say they are watching this extremely closely. steven east at isi says, i do think cancellations will climb. he said the 100 basis point rise we've seen affects the monthly payment by 13%, and he says that can be make or break to many buyers. we've got a lot more of this, a lot more analysis online. realty check .cnbc.com. >> is morning fo