According to Wiki, "exogenous" comes from the Greek words "exo" and "gen", meaning "outside" and "production" and refers to an action generated from outside the system. I have written about this in the past.

This morning "MarkM" commented that "miners are not liking this rarified air. Need to improve relative performance or that has been a reversal signal; Gold up, HUI and XAU down (10:50am). If gold decides to correct before decisively crosssing $600 (I would be surprised), I am looking at $575 area as first line of resistance. 50dma and 200dma are quite some ways away though. $620 looks to be target here."

First, I ran an overlay of the Toronto Stock Exchange Goldminer index (XGD) (in blue in the chart below) against the GLD ETF this morning. The goldminer stocks opened comparatively stronger, but then, as MarkM points out, have been underperforming the spot gold price.

I believe this picture is showing that traders will trade Gold in the short term based on exogenous events more so than they are inclined to trade goldminer stocks that way.

That simply means that traders are not yet believers that, in the present circumstances, the U.S. Administration concern over Iran's presumed weaponization of its nuclear program is anything more than sabre-rattling.

With respect to the goldminer stocks, I believe traders are more interested in the $USD strength, and rising labor rates and energy costs of the gold producers.

Tomorrow that might change, but for now, I think gold bullion traders are looking at Iran, which is an exogenous event, and goldminer traders are looking at historical pricing models.

btw, James OShaunghnessy of Bear Stearns was just explaining a Quantitative measure he uses, which is Price to Sales. This is not a Technical measure, like Relative Strength Index. This is a query I receive frequently, but you all should be aware that "technical" is different from "quantitative".