The electric vehicle maker still looks deeply undervalued.Rivian Automotive's (RIVN -5.23%) stock tumbled 7% on Aug. 7 after it posted a mixed second-quarter report. The electric vehicle (EV) maker's revenue rose 3% year over year to $1.16 billion and exceeded analysts' expectations by$20 million.But its net loss widened from $1.2 billion to$1.46 billion, or $1.46 per share, missing the consensus forecast by$0.21. It slightly narrowed its adjusted earnings before interest, taxes, depreciation, and amorti ...