Each week, The Fly will announce the newest downgrades to Strong Sell in StockNews.com's POWR Ratings algorithmic model.

This Fly exclusive recap identifies stocks with over a $1B market capitalization that have been downgraded this week to the Strong Sell, or "F," rating in the service's proprietary model that analyzes 118 different factors, each of which contribute a little to the stock's predicted likelihood of underperformance. A bell curve distribution of StockNews.com's ratings shows that only the top 5% of the over 5,000 stocks rated by the system are assigned a "Strong Buy," or "A," rating while the bottom 5% are assigned a Strong Sell. The F-rated stocks would have tumbled an average of 18.98% a year since 1999, according to StockNews.com.

This week's downgrades to Strong Sell as determined by the POWR Ratings algorithm:

• Healthcare Realty Trust (HR) - a real estate investment trust that integrates owning, managing, financing and developing income-producing real estate properties associated primarily with the delivery of outpatient healthcare services
• Bilibili (BILI) - operator of a video community for young generations in China
• Norwegian Cruise Line (NCLH) - a global cruise company which operates the Norwegian Cruise Line, Oceania Cruises and Regent Seven Seas Cruises brands
• AST SpaceMobile (ASTS) - a cellular cellular broadband network meant to work in space
• Cronos Group (CRON) - a global cannabinoid company with an international portfolio of cannabis product brands
• Krystal Biotech (KRYS) - a pivotal-stage gene therapy company

Learn more about the POWR Ratings

The Fly's recent reporting on these stocks includes:

Yesterday, the Wall Street Journal reported that the U.S. and China are nearing an agreement that would allow American accounting regulators to travel to Hong Kong to inspect the audit records of Chinese companies, including Bilibili (BILI), listed in New York and regulators in Beijing are making arrangements for U.S.-listed Chinese companies and their accounting firms to transfer their audit working papers and other data from mainland China to Hong Kong, which could prevent many Chinese companies from being delisted from American stock exchanges.

Last week, AST SpaceMobile (ASTS) reported a year-over-year increase in second quarter earnings per share and revenue, though it still reported a loss for the quarter. Following the report, Deutsche Bank analyst Bryan Kraft lowered the firm's price target on AST SpaceMobile to $30 from $31 and kept a Buy rating on the shares, saying he remains bullish on AST's long-term business opportunity.

Earlier this week, Goldman Sachs analyst Madhu Kumar downgraded Krystal Biotech to Neutral from Buy with an unchanged price target of $74. The analyst cited valuation for the downgrade following the stock's outperformance driven by the Phase 3 success for its herpes simplex virus gene therapy Vyjuvek for dystrophic epidermolysis bullosa. The analyst awaits continued regulatory progress for Vyjuvek and downstream pipeline readouts "to potentially become more constructive."