While Fools should generally take the opinion of Wall Street with a grain of salt, it's not a bad idea to take a closer look at particularly stock-shaking upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of Netflix (NASDAQ:NFLX) rallied 3% today after Morgan Stanley upgraded the video-streaming service giant to overweight.

So what: Along with the upgrade, analyst Benjamin Swinburne planted a price target of $500 on the stock, representing about 16% worth of upside to yesterday's close. So while contrarian traders might be turned off by Netflix's price strength over the past month, Swinburne's call could reflect a sense on Wall Street that its long-term growth prospects give the stock plenty of room to run.

Now what: According to Morgan, Netflix's risk/reward trade-off is rather attractive at this point. "By 2020, we see the int'l broadband TAM increasing to ~280mm HHs, with NFLX's penetration doubling to ~20%," said Swinburne. "While this outlook may appear bullish, we believe it is achievable particularly given success in Canada, the UK and the Nordic regions. Further, the ubiquity of broadband, proliferation of connected devices, and arbitrage opportunity of serialized programming should allow NFLX to scale int'l and drive long-term margins." Of course, with Netflix shares still up about 115% from their 52-week lows and trading at a 60-plus forward P/E, I'd wait for a pullback before buying too heavily into that bullishness.