some energy names benefiting from this. 4% gains for halliburton and sl schlumberger. ticker symbol wrk soaring in its debut. it opened at $38.50 and is off the highs, with a gain of 55% in its debut day. what is a direct listing? it saves slack money in fees, allows shareholders to sell their stock without all the restrictions you see in a traditional ipo. slack is a workplace messaging and communication platform. still unprofitable, i remind you, but it gets a valuation of around $23 billion. we'll see if airbnb or any of these other unicorns pursue direct listings as well. >>> president trump kind of spoiled the market parade today. he tweeted at 11:15 a.m. in response to iran's shooting down a u.s. drone, quote, iran made a very big mistake and markets dipping again later in the day when president trump answered a question about whether the u.s. would retaliate. listen. >> iran made a big mistake. this drone was in international waters, clearly. we have it all documented. obviously you know we're not going to be talking too much about it. you're going to find out.