Shares of Irvine-based nursing home operator Sun Healthcare Group Inc. fell sharply today after first-quarter revenue came in below analysts’ expectations.

Sun’s shares were down about 17% in midday trading, giving the stock a market value of about $147 million.

The company’s profit from continuing operations totaled $1.8 million, in line with analysts’ estimates.

But quarterly revenue fell 2% from a year earlier to $458.5 million, missing analysts’ consensus expectations of $474.4 million.

Sun Healthcare said the revenue drop was tied to Medicare reimbursement cuts.

The company said it was able to “achieve results in line with our expectations” despite the dual challenges of Medicare and weakened external demand.

Sun Healthcare did not offer Wall Street guidance for the current quarter.

Analysts on average expect Sun to post a profit of $3.4 million on revenue of $476.7 million in the second quarter.