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 Marketo (NASDAQ:MKTO) closed up 1.2% yesterday after Wells Fargo initiated coverage on the cloud-based marketing software specialist with an outperform rating.

So what: Along with the outperform call, analyst Jason Maynard offered a valuation range of $40-$42 per share on Marketo, suggesting that the stock is trading at about a 25% discount to its intrinsic value. Maynard believes that Marketo is an emerging leader in what he refers to as the "Big Customer Era" -- power shift in favor of the customer across both business-to-consumer and business-to-business segments -- reinforcing investor optimism over the strong tailwinds working in its favor.

Now what: In total, Wells Fargo sees the "big customer" marketing automation space growing to $20 billion in five years and expects Marketo to grab a nice chunk of that.

"We think Marketo has the potential to grow in excess of 25% for the next several years because of the following business drivers: (1) increasing budget allocation for revenue- generating software solutions, (2) aggressive customer acquisition, (3) cross and up-selling in the installed base, (4) product fit for SMBs to larger organizations, and (5) increased penetration in B2C market segment."

More important, with the stock still off about 20% from its 52-week highs and trading at a forward EV-to-sales multiple in the single digits, there seems like plenty of upside to benefit from that bullishness.

Fool contributor Brian Pacampara has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.