Shares of XPO Logistics, one of the largest transportation and warehouse companies in the world, plummeted more than 12 percent Friday after reporting weaker-than-expected earnings and issuing a dire warning about its business in 2019.

XPO Logistics posted adjusted fourth-quarter earnings per share of 72 cents on Thursday, well below a Refinitiv estimate of 84 cents. The company's revenue also missed expectations. XPO also said that a reduction in business from its largest client — who was not identified — would negatively impact its growth this year.

Those results sent XPO's stock on its worst daily decline since Dec. 13, when it fell 26.17 percent.

"Reading between the lines, we believe the shipper that is paring down its parcel injection, brokerage, last mile, and logistics activity with XPO is Amazon," J.P. Morgan analyst Brian Ossenbeck said in a note. "Given the e-tailer's efforts to expand its logistics capabilities, we expect the market will interpret the XPO contract loss as Amazon taking capacity in-house which is negative for [FedEx] and UPS."

Ossenbeck kept his overweight rating on the stock, but trimmed his price target to $78 per share from $84. The revised price target implies a 31 percent upside over the next 12 months.

Amazon declined to comment. FedEx and UPS shares were both down on the day.

XPO shares had already fallen sharply prior to Friday's decline. The stock was down more than 24 percent over the past three months through Thursday's close. It was also down 40.4 percent over the past six months.

"NET/NET while we fully understand the initial negative reaction, we do not think the fundamental story is broken," Deutsche Bank analyst Amit Mehrotra wrote in a note. "Nonetheless, [Thursday's] release clearly puts the company deeper into the penalty box."

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