It was back to reality Monday for Rite Aid (RAD) - Get Report investors, with the drugstore chain's stock tumbling hard after a dramatic run-up over the past week and a half.

Rite Aid's stock price plunged 14.82% to $17.29 a share, continuing a decline that began late Friday after the pharmacy giant peaked at above $21 a share.

The slide comes after more than a week of big gains for the stock. The drugstore chain's stock, which had been trading at around $8 a share, more than doubled in value in the week following Rite Aid's release of better-than-expected third-quarter earnings.

Rite Aid reported quarterly earnings of 54 cents a share on Dec. 19, beating the estimate of 3 cents a share of analysts surveyed by Zacks Investment Research.  That was up from 28 cents during the same quarter in 2018.

Rite Aid also posted a narrow beat on revenue, reporting $5.462 billion for the quarter compared to the $5.428 billion estimate of analysts polled by Zacks.

Pharmacy services revenue rose 5.7% amid an increase in Medicare Part D membership, even as retail pharmacy sales edged down 1.7% amid a decline in the number of Rite Aid stores across the country.

The earnings surprise and the recent surge in Rite Aid shares came amid a tougher, overall picture for the pharmacy chain, which has been losing market share to competitors like CVS Health (CVS) - Get Report.

Still, even as investors jumped on the Rite Aid bandwagon, analysts have been far more measured in their outlook.

Over the past two months, there have been no upward revisions by analysts of their estimates for Rite Aid's current, fourth-quarter earnings, with the only change being a downward revision by one analyst, according to Zacks.