Wall Street loves

Salesforce.com

(CRM) - Get Report

, but investors are wondering if shares of the upstart software vendor are getting too expensive.

The stock got a jolt Monday, when CSFB analyst Jason Maynard downgraded it to neutral from outperform, saying "shares have increased nearly 50% since the last earnings call, leading us to believe that in the short-term much of the good news has been priced into the stock."

Maynard, whose firm has an investment banking relationship with Salesforce, was quick to note, however, that "we have nothing but love for Salesforce's model."

In recent trading, shares were off $1.29, or 5.9%, to $22.24, on a day when most tech issues, including software stocks, were up.

The skeptics surfaced last week, buying a notable number of puts and selling call options, said Stacey Briere, chief options strategist for the Susquehanna Financial Group.

"Due to the presence of put buyers and call sellers, we believe there is a greater likelihood of a downside move," Briere said in a note to clients. Susquehanna does not have an investment banking relationship with Salesforce.

Salesforce will report earnings after the closing bell Wednesday amid "sky high" expectations, as one analyst put it; and living up to those lofty hopes may be difficult -- one explanation for the options activity.

Salesforce.com leases and runs its customer relationship management software via the Web. Although its software is not as robust as conventional enterprise software sold by

Siebel Systems

(SEBL)

and others, it has found a substantial niche in the market and is taking lower-end business off the tables of its competitors.