Quite the nice rebound in MBS this afternoon as we've recaptured almost half of the losses on the day.  If you're lender is a laggard, they still may just be releasing a reprice for the worse.  If their ahead of the curve the reprices should be hitting now.  If you already got a reprice for the worse, or if your lender is diligent about getting out reprices in a timely manner, then floating for the rest of the business day makes sense, but with the boatload of data tomorrow, and a stock market that is just itching for an excuse to go higher, it's a dangerous play.  The data is diverse tomorrow and all relatively important, so a lot of the movement will depend on traders interpretation of the data as opposed to the raw data itself. 

There are arguments to lock and arguments to float.   Since the 5.5 coupon has just barely crept into 99-00 territory, there is certainly plenty of room for it to move back up if the data is weak.  But if the market decides it wants to rally, there's not a ton of resistance to keep it from going lower as well.  If you force me to take a stand, then I would float with all but the deals that will die if rates get higher.  The technical data is there to allow a little bounce for us tomorrow, especially with the 4 days of declines in a row.

The economic data is the dark horse though, and this is where you need to use your judgment.  First, Incomes and Outlays is calling for a decrease in cash received from .5% to .2% and an increase in spending from .1% to .2%.  You can research the historical data on Bloomberg and see if you think analysts have it right.  If spending is higher than expected, rates will move higher as well (or at least this is a stimulus for rates to move higher).

Execute the same research for NAPM and consumer sentiment.  Those ones are a little more intuitive.  If either one is higher than expected, this is also a force that can push rates higher.  Neither are quite as potent as a surprise income and outlay report, but the NAPM in particular has been more impactful in recent months.  Consumer sentiment is fairly meaningless unless it deviates wildly from expectations, but analysts seem to have their finger on the pulse of consumers finally (flatliners, all of them).

So if you are not the borrower on the loan in question, perhaps it is best to educate the borrower on the risk versus reward and leave the float/lock decision to them.  If they defer to you, the only rate you can guarantee is the one that you can lock right now.  If you want to put your income on the table and spin the wheel, that's up to you.  As I said, I will be doing that with some of my chips tomorrow and others I can't afford the buy-in.  But don't get swayed by opinion.  If you're going to be "day-trading" with your floats/locks, you'll learn much quicker if you look at the data for yourself and take your own stand.  Trust your feelings.  Sure you'll always be able to get an opinion here, but when in doubt, use the force!