Updated from 11:30 a.m. EDTSAN FRANCISCO -- The three-day, 17% jump in shares of Research In Motion ( RIMM) leading into Friday may be the end of the road for now, according to one analyst. On Friday, ThinkEquity analyst Mike Burton initiated his coverage with a sell rating and a price target of $30, citing the need for future earnings estimates to come down. Shares of RIM were recently down 4.1% to $39.76. Burton cited the standard concerns about the state of the smartphone and handset market this year -- that a downtrodden consumer and continually expanding competition are going to spell trouble for future profit margins. Apple ( AAPL) and Nokia ( NOK) are merely the more well-known rivals, while others prepare to enter the field. In addition, Burton writes, "We have been hearing that carriers are asking for price reductions across all vendors including those at the very high end of the value scale." The analyst also sees a margin squeeze from price concessions that will come from the growing layoffs and cost-cutting by its corporate customers, which, if you believe estimates that one in 10 Americans will eventually be out of work, doesn't bode well for subscriber growth and replacement demand. Burton expects RIM to earn $3.24 a share in fiscal 2009, and $2.79 in fiscal 2010. Both estimates are significantly below average analyst estimates of $3.38 for 2009 and $3.61 for 2010.