Yesterday afternoon, the S&P 500 closed at a record high, and is up over $1.5 trillion since the start of 2017. "And the companies doing the most to drive that rally are all tech firms," reports The Verge. "Apple, Alphabet, Facebook, Amazon, and Microsoft make up a whopping 37 percent of the total gains." From the report: All of these companies saw their share prices touch record highs in recent months. This is in stark contrast to the rest of the U.S. economy, which grew at a rate of less than 1 percent during the first three months of this year. That divide is the culmination of a long-term trend, according to a recent report featured in The Wall Street Journal: "In digital industries -- technology, communications, media, software, finance and professional services -- productivity grew 2.7% annually over the past 15 years...The slowdown is concentrated in physical industries -- health care, transportation, education, manufacturing, retail -- where productivity grew a mere 0.7% annually over the same period." There is no industry where these players aren't competing. Music, movies, shipping, delivery, transportation, energy -- the list goes on and on. As these companies continue to scale, the network effects bolstering their business are strengthening. Facebook and Google accounted for over three-quarters of the growth in the digital advertising industry in 2016, leaving the rest to be divided among small fry like Twitter, Snapchat, and the entire American media industry. Meanwhile Apple and Alphabet have achieved a virtual duopoly on mobile operating systems, with only a tiny sliver of consumers choosing an alternative for their smartphones and tablets.