GameStop isn't the only sign of froth, experts warn
The stock shot up more than 70% in early afternoon trading Friday
Alongside GameStop shares, BlackBerry stocks also carry a warning
Value stocks outperformed growth stocks in the fourth quarter
Robinhood, Charles Schwab and TD Ameritrade are among the brokerages restricting trades
Short sellers are coming up against retail investors determined to maintain the videogame retailer's momentum
Uncertainty abounds, but 2021 promises opportunities in equities markets
A report looks at whether this is the end of the current cycle or the start of a new one
The S&P 500 slipped 0.2%, pulled down by losses in banks and communications companies
The S&P 500 fell 0.4% Monday, its second straight drop after setting its record on Thursday