I am wondering how margin calls could have been a contributing factor in the price decline. 

I have never bought on margin, so I am quite uninformed about that.

The Venture Exchange website, though, indicated that the margin requirement is 100%, for shares selling under $3.00.  Does that mean, in effect, that margin buying is not permitted for these low-priced stocks?

Hope my question is not too dumb.

(I hold some shares, and I am NOT selling.)