(Bloomberg) — A Hong Kong stock that had soared nearly 450% the past year plunged in its first trading day as a member of an index compiled by MSCI Inc.

Perennial Energy Holdings Ltd., a coal miner based in China’s southern Guizhou province, slumped a record 69% Friday to an eight-month low. Its addition to the MSCI China Index was announced earlier in May as part of a quarterly review.

Perennial dramatically pared a one-year gain of 446% through Thursday — when trading turnover in the stock hit a record high of HK$1.3 billion ($168 million). By the close of trade on Friday, the year-over-year advance was just 68%.

A company representative said they could not immediately comment on the share decline when contacted by Bloomberg. A spokesperson for MSCI didn’t immediately respond to a request for comment.

Perennial’s net income jumped 58% last year, but its free cash flow has been negative for two years, according to data compiled by Bloomberg.

It’s not the first time that a company selected by MSCI has quickly slumped upon joining one of its benchmarks. Hebei Construction Group Corp. tumbled 60% in Hong Kong on Dec. 1, the first day it was in the MSCI China All Shares Index. ArtGo Holdings Ltd., which had soared almost 3,800% in 2019, erased nearly all of that advance in minutes after MSCI dropped plans to add the stock to its measures.

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