** Elon Musk's SpaceX SPCX.O set to begin trading on Nasdaq later on Friday after raising $75 billion in the world's biggest IPO ever

** SPCX sold 555.56 million shares at $135 apiece, valuing the rocket and satellite maker at $1.77 trillion

** SPCX set to make the first U.S. trillion-dollar debut and become the seventh-largest U.S. company by market capitalization

** At $75 billion, deal's proceeds were more than double those of Saudi Aramco's record-setting 2019 IPO

** SPCX estimates its market ​opportunity spans $28.5 trillion, a figure it called the largest ​in human history

** U.S. space stocks have also gotten a boost ahead of SpaceX's hotly anticipated debut on hopes of higher valuations

** Some are also buying Virgin Galactic SPCE.N on bets that the stock will get lift from investors confusing it with SPCX

** Elsewhere, Oppenheimer on Thursday initiated SpaceX coverage with a bullish rating and $190 PT

** Goldman ​Sachs, Morgan Stanley, BofA Securities, Citigroup and J.P. Morgan were among joint book-running managers for SpaceX's offering