Lumber down 30% in a month. Homebuilders React

With Lumber prices getting destroyed, one thing comes to mind: Homebuilders. If there's demand for new homes, you're going to need some lumber. If there is less demand for new home construction, you are going to need less lumber. Plain and simple. We also use Lumber Prices as a heads up for moves in Treasury Bond Prices (but that's for another day). Let's take a look at $XHB:

Lumber prices are down 30% per board feet in just one month. This comes at a time when the S&P Homebuilders Index ETF closed at the highest levels in almost a year. $XHB closed at $18.82 both Wednesday and Thursday. We're going to watch this closely for any false moves because both these new highs came on disappointing intraday action and non-existent volume. RSI has held in Bullish mode, for now, so that's one positive.

The problem lies in the components. With the ETF making new highs, none of the usual suspects are participating. Toll Brothers ($TOL), Lennar Corp ($LEN), KB Homes ($KBH), Pulte Group ($PHM), and MDC Corp ($MDC) are all well below their Year-to-date highs. What seems to be the problem? Are Lumber prices warning us that something is wrong with this group? Is the lack of participation from the Homebuilding stocks confirming the lumber warning? A 30% hit in a month gives us reason to watch closely. The mixed signals and lack of component confirmation makes me worried.