Starbucks Corp shares fell nearly 7 percent on Friday to their lowest in more than 4 years, sparked by the coffee shop chain's admission that customer traffic slowed for the first quarter in its history.

The seller of premium coffee, which coaxed U.S. consumers into drinking stronger, more expensive coffee, said U.S. traffic at its established locations fell 1 percent in the quarter as economic worries and 2 percent price rises spooked consumers.

Starbucks shares traded at about 21 times next year's estimated earnings on Friday, less than half their peak valuation of 45 about 18 months ago. Once viewed as a high- flying growth company with unrivaled expansion opportunities, Starbucks now trades in line with McDonald's Corp and at a discount to Yum Brands Inc and Wendy's International Inc, which have multiples of about 23 and 24, respectively.

Relative to other casual dining/quick service companies in our coverage with similar/lower growth rates, Starbucks can perhaps (for) the first time in its existence be thought of as a relative value, wrote J.P. Morgan analyst John Ivankoe in a research note.

Ivankoe has an overweight rating on the shares, but noted he considers that rating our major mistake of 2007.

Goldman Sachs analyst Steven Kron expects little change in sentiment on the stock in coming months and thinks expectations are reasonable with today's known factors.

Though difficult to quantify, we attribute much of the weakening traffic to the macro environment which continues to weigh on restaurants broadly, Kron wrote.

Starbucks shares were down 99 at $23.11 on the Nasdaq in late afternoon trading, after falling as low as $21.77 earlier in the session.