The Next Tech Crash Could Delay Your Retirement By A Decade

``The first warning sign is the current number of IPOs. After rising to 275 new listings in 2014, IPO activity dropped off to just 105 last year, a sign that companies are finding it harder to attract capital at desired valuations... Another notable development is the concentration of companies making up the NASDAQ. The combined market caps of Apple (AAPL), Alphabet/Google (GOOGL), Microsoft (MSFT), Facebook (FB), and Amazon (AMZN) now exceed $3 trillion--that means these five companies comprise almost a quarter of the entire $12.5 trillion index containing more than 3,100 companies...'' -- See also DOT COM Bubble Do-Over?.