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 Teradata (NYSE:TDC) sank 3% this morning after Goldman Sachs downgraded the analytic data solutions company from neutral to sell.

So what: Along with the downgrade, analyst Greg Dunham lowered his price target to $36 (from $48), representing about 18% worth of downside to yesterday's close. While momentum traders might be turned off by Teradata's weak stock price in recent months, Dunham believes there's more room to fall given the intense competitive pressure that continues to weigh on the company.

Now what: Goldman now expects Teradata to post 2014 earnings per share of $2.84 on revenue growth of 4%, down from its prior view of $3 and 8%. "While we continue to see the company as well positioned in the Enterprise Data Warehousing (EDW) space and expect growing spend on traditional analytics projects, we believe headwinds from increased EDW optimization through more widespread use of Hadoop will create a drag on growth," noted Dunham. "Although the sell-off (the stock is down 26% over the past three months) makes the stock seem attractive, we do not believe the secular story will get any easier over the next few years and do not believe a snapback in spend will be sustained for more than couple quarters." Given Teradata's rock-solid balance sheet and forward P/E in the low teens, however, the downside might be limited enough to actually buy into its EDW growth prospects.