If the stock still experiences significant fluctuations, surpassing 50%-100%, the Securities and Exchange Commission will quickly intervene for an investigation and temporarily suspend trading.
Once they confirm there's no mysterious force other than the market influencing and maliciously manipulating stock prices, they will resume normal trading.
That stockbroker claimed they could triple the price within half a day, indeed it's achievable, which means the private equity funds must have the people at the Securities and Exchange Commission in their pocket. While halting trading, it will also attract countless retail investors to enter the market until the stock price is pumped to a high.
If one could know at what price to enter and at what price to exit precisely, then even a pig could make money from the stock market!
Just a flick of the finger, and millions of US Dollars are in hand, operations are that simple.