you can never trust pre or post market trades unless they are high volume..Often some traders or hedge funds who may also be long trade a few hundred shares in several trades in the same accout--e.g.-- they are on the buy side and the sell side at a premium to the closing price. The trades are net neutral for them. They do this to lure some unsuspecting buyers to think something good is going to be announced soon which entice them to buy shares from them at the inflated price. These naive buyers will then find out at the openning that they were duped.
yeah, I know about that. thought maybe somebody typed in the wrong number too in PM and got burned. vrtx won't hit 48 until it has good news. With GILD's HEP C drug soon to be approved, VRTX will drop again towards 40.