I don't know why I thought it was 1990s that it was established, the signing of the order was 1988. I'm either confusing it with something or thinking of some follow up document in 1991. The P/Es have nothing to do with PPT. They went out of whack during the 80s bull market and the real cause was US going off the gold standard hence unhinging money supply completely. PPT's purpose is not to prevent every plunge, it is to manipulate the market on behalf of the true big boys. They do like to squeeze the shorts of the retail players.
Perhaps, but that happened in '71 and the P/E didn't explode until the 90s, so there must be another cause.
Money supply started ramping up in the 1980s. Reaganomics (aka give money to corporates) and junk bonds were big drivers. That was really the beginning of the Financial industry becoming the backbone of the economy.