Quantitative trading companies are spending more and more money to trade faster, because the barrier to entry continues to plummet. For example, they used to in

Quantitative trading companies are spending more and more money to trade faster, because the barrier to entry continues to plummet. For example, they used to install software programs on computers, now they actually hard-wire programs directly to motherboards to shorten the execution time. As the article mentioned, trading firms are investing heavily into expensive fiber optic lines instead of traditional internet. For these reasons and many more, the fraction of a penny that each trade earns them also continues to grow smaller as the arbitrage that they trade on grows smaller because every firm is investing into the same expensive strategies.