"Still, some analysts urge DWA investors to sell today."
This is just negotiation. DWA jumped up from $2.3B market cap to $2.8B market cap. If Comcast wants a $3B purchase price, they need to offer full market cap + some amount of top of that. So, they'll start slowing talks, wait for the stock to go back down, and then buy the company.
Not saying it's a done deal, but wait until the deal is dead before taking stock (pun intended) in this.