By Dave Sebastian

Marriott International Inc. swung to a loss for the second quarter as it missed out on a usually lucrative summer travel season amid the Covid-19 pandemic.

The hotel operator on Monday posted a loss of $234 million, or 72 cents a share, compared with a profit of $232 million, or 69 cents a share, in the same quarter last year.

Adjusted losses were 64 cents a share, wider than the 41 cents a share loss analysts polled by FactSet were expecting. The company incurred impairment charges and bad-debt expense due to Covid-19 that hurt reported and adjusted losses by $61 million and $54 million, respectively, after taxes.

Comparable systemwide revenue per available room, a closely watched industry metric also known as RevPAR, fell 84.4% for the quarter. Occupancy fell 57.4 percentage points. Those figures have improved from April lows, when RevPAR was as low as down 90% and occupancy bottomed at 11% for the week of April 11, Chief Executive Arne Sorenson said.

"While our business continues to be profoundly impacted by Covid-19, we are seeing steady signs of demand returning," Mr. Sorenson said.

Mr. Sorenson said 91% of Marriott hotels world-wide have reopened, with the Greater China region, where all the company's hotels have reopened as of early May, leading the recovery. In North America, 96% of Marriott hotels are open, he said.

The Bethesda, Md., company said revenue fell 72.4% to $1.46 billion. Analysts were looking for $1.68 billion.

Write to Dave Sebastian at dave.sebastian@wsj.com

Corrections & Amplifications

This article was corrected at 08:00 a.m. ET because the original incorrectly stated RevPar for April. Those figures have improved from April lows, when RevPAR was as low as down 90% and occupancy bottomed at 11% for the week of April 11, Marriott Chief Executive Arne Sorenson said.