Charles Schwab's (SCHW) earnings and revenue narrowly missed analysts' expectations despite strong trading activity, but the stock held up at a critical level. The brokerage firm early today reported adjusted earnings of $1.39 a share, a year-over-year increase of 38$1.40 a share. Fourth-quarter revenue climbed 19% to $6.336 billion, just below projections for$6.38 billion,… ...