For many funds and institutions, $5 per share or a $500M market cap are magic numbers. As the price moves above $5, the number of funds and institutions that can buy ATRS will increase. Indeed, one of IBD's buying rules is to buy stocks that are selling at or above $15. IBD states the same reason to support its $15 or higher rule that we state here at $5. That is, the number of big buyers at $15 and above is significantly higher than below $15. To that end, the higher we go, the more buyers waiting to step in and take us higher.
I don't think that is set in stone for all funds. Some can buy now, some use the market cap. The heavy volume over the last couple weeks was not caused by retail investors buying. I think fund buying will be increasing leading up to and after the upcomming CC.