(Bloomberg) -- China is censoring crowd-sourced documents tallying the number of mortgage boycotts spreading across the country, potentially hampering a key source of data for global investors and researchers tracking the property crisis. 

Shared files managed on platforms including China’s Quora-equivalent Zhihu Inc. and on sites like Kdocs and Wolai have been banned following reports that the number of homebuyers refusing to pay mortgages surged in a span of days. GitHub, a popular file-sharing site for coders, remains as a source for people to post documents.

The file sharing has provided a key battleground for homeowners who are shunning mortgage payments for apartments that haven’t been built on time. The information also offered a gauge for global investors and banks from Nomura Holdings Inc. to Citigroup Inc. to measure the scale of the unfolding protests. 

Lenders have said the bad housing loans are controllable. But the spike in incidents is fueling concerns that the property troubles -- which have largely centered on developers following a government crackdown on excess leverage -- will engulf big banks and China’s middle class, who have an estimated 70% of wealth stored in real estate. 

“This is a political protest,” Diana Choyleva, chief economist at Enodo Economics, said in an interview on Bloomberg Television. “It’s not going to be a banking crisis, they are not there. But it a crisis potentially of confidence and one that the Chinese Communist Party fears tremendously.”

Information shared on the platforms included names of projects that were stalled, and images of letters from homebuyers declaring that they refused to pay. GitHub’s page on the topic was starred, or bookmarked, by more than 14,000 users. 

Homebuyers complained that their social media accounts on TikTok’s Chinese cousin Douyin and the Twitter-like Weibo have also been banned. Some buyers who asked not to be named said they were contacted by police. 

Posts on WeChat and Weibo containing snapshots of charts tallying mortgage boycotts or project delays were deleted. Among them was a July 13 analysis by property researcher China Real Estate Information Corp. which showed homebuyers stopped mortgage payments on at least 100 projects in more than 50 cities. 

The Cyberspace Administration of China didn’t immediately respond to a faxed request for comment. 

The mortgage boycotts have alarmed investors, dragging down the stocks and bonds of property firms including China Vanke Co. and Country Garden Holdings Co., as well as the nation’s biggest lenders. A benchmark stock index for Chinese banks fell 7.7% this week, the most in four years.

Chinese authorities held emergency meetings with major banks this week to discuss the home-loan snub on concern that more buyers may follow suit, according to people familiar with the matter. Some lenders plan to tighten their mortgage lending requirements in high-risk cities, two of the people said.

Banks are rushing to reassure investors that risks are contained. Lenders have detailed 2.1 billion yuan ($311 million) of loans at risk. In most cases, the overdue amount makes up less than 1% of the lender’s total mortgage portfolio. However, GF Securities Co. expects as much as 2 trillion yuan of mortgages could be impacted. 

Nomura said the refusal to pay mortgages stems from the widespread practice in China of selling homes before they’re built. Funds from presales are kept in escrow accounts to use for construction. But confidence that projects will be completed has weakened as developers’ cash woes intensified. 

“Inappropriate usage of presale proceeds and the lack of adequate supervision of escrow accounts by local regulators and banks are likely associated with these mortgage suspension cases,” Zerlina Zeng, a senior analyst at CreditSights, wrote in a note.  

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