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As the one-year anniversary of a crisis that brought down several midsize banks approaches, trouble at another lender is putting unwelcome attention on the industry again.

Concerns now center on New York Community Bancorp, which operates roughly 400 branches nationwide under brands such as Flagstar Bank and Ohio Savings Bank. The bank ballooned in size over the past year, to more than $100 billion in assets, after taking over the fallen Signature Bank last spring in an auction organized by federal regulators.

New York Community Bancorp’s stock nose-dived after it released an ugly earnings report that included unexpected losses on real estate loans tied to both office and apartment buildings. Its shares have lost about half their value over the past week.

Shares of other lenders with portfolios of commercial real estate have dropped, too, a reminder that what afflicts one lender can affect others, as when fears about concentrated customer bases and low-rate bond portfolios took down a group of lenders last spring. Here’s what you need to know.

What is behind the latest banking worries?

The principal shock in New York Community Bancorp’s earnings report last week came from its admission that the value of its real estate loans had dropped steeply, which spurred it to slash its dividend and sock away half a billion dollars to protect against future losses. The bank identified a pair of loans in particular — one related to an office complex and another for a co-op residential building — that were responsible for as much as $185 million in losses.

Bank representatives, who did not respond to requests for comment, fueled further angst by deflecting analysts’ questions about their expectations for future profits. The bank’s stock plummeted nearly 40 percent after the earnings report and have continued to lose ground, falling 11 percent on Monday and dropping more than 10 percent in early trading on Tuesday.