2020 was a record year for the US stock market. The S&P 500 index, which includes 500 of the top US-listed companies, closed the year up 16% to a then-record of 3,756. With the optimism surrounding the stock market, 2020 saw a huge uptick in initial public offerings (IPOs) as well, setting a new high. According to FactSet, the number of IPOs in 2020 more than doubled to 494, compared to the previous year. In all, IPOs raised US$174 billion in 2020, a 150% increase over 2019. Fun fact: Special purpose acquisition companies (SPACs) accounted for 50% of all IPOs in 2020. Source: FactSet The flurry of IPO activities is continuing well into this year. 2021 debutants include gaming company Playtika (NASDAQ: PLTK), buy now pay later player Affirm Holdings Inc (NASDAQ: AFRM) and dating app Bumble Inc (NASDAQ: BMBL). While IPOs may have plenty of promise, I tend not to invest in them as they are usually expensively-valued....