In a stunning reversal that may indicate gun sales won't be booming in advance of potential new legislation, stock prices for America's leading firearm manufacturers dove quite a bit in the first day of trading after the shootings at Sandy Hook Elementary, reports Bloomberg:

Smith & Wesson dropped 3.3 percent to $8.83 at 1:38 p.m. in New York, extending the decline to 7.4 percent over two days after the Dec. 14 shooting. Sturm Ruger & Co. (RGR) has fallen 6.8 percent during the period [...]

Today Smith & Wesson closed at $8.65 (from $9.54 on December 13, the day before the shooting in Newtown), and Sturm Ruger at $44.00 (from $47.73 on that same day).

Bloomberg points to "speculation President Barack Obama will renew a ban on assault weapons," which picked up momentum after Sen. Dianne Feinstein said she would propose it, despite potential pushback in the House.

It's a sudden turn of events given that the same stocks went up following Obama's re-election in November. Per MSN Money:

Investors think the stocks have farther to go, propelled by fears that Obama will crack down on guns in his second term.

So it's unclear: why are these stock prices going down if the imminent threat of stricter gun policy was supposed to explain their rise? Over at Slate, Matthew Yglesias pointed to two factors in explaining the rise in Ruger's 500-percent rise since Election Day (pictured below): "a general upward trend for manufacturing enterprises since the lows of the recession," and "the phantom menace of Obama's gun grab has inspired a lot of people to double-down on their weapons purchases."