Here’s why an Apple bear changed his tune by Philip Elmer-DeWitt @FortuneMagazine August 26, 2015, 8:18 AM EST E-mail Tweet Facebook Linkedin Share icons Two things happened Monday to cause Wells Fargo’s Maynard Um—a long-time Apple bear—to upgrade his rating on Apple’s shares from market perform to outperform. The stock fell to $92 per share, $33 below the low end of his valuation range ($125-$135) Tim Cook told Jim Cramer that iPhone sales growth hasn’t slowed in China “While we note that our fundamental stance on Apple’s challenges are unchanged, we believe shares have over-corrected. Tim Cook’s email to CNBC’s Jim Cramer that iPhone activation growth in China “has actually accelerated over the past few weeks…” gives us better visibility to the Sept quarter.” To illustrate how far that over-correction has gone, Um offers the chart below. Click to enlarge. By comparison, the average S&P 500 price/earnings ratio as of Tuesday’s close was 18.82. Follow Philip Elmer-DeWitt on Twitter at @philiped. Read his Apple AAPL coverage at fortune.com/ped or subscribe via his RSS feed.