UPDATE 4-China to base new lending benchmark on medium-term rates; shares rally on rate cut hopes

(Adds Moody's comment)

By Kevin Yao and Samuel Shen

BEIJING/SHANGHAI, Aug 19 (Reuters) - China's announcement of key interest rate reforms over the weekend has fuelled expectations of an imminent reduction in corporate borrowing costs in the struggling economy, boosting share prices on Monday.

The People's Bank of China (PBOC) unveiled the long-awaited reforms on Saturday to help steer borrowing costs lower and support businesses hurt by weak demand at home and a year-long trade war with the United States.

While the rate overhaul has been in the works for some time, the announcement came days after data showed the economy stumbled more sharply than expected in July, raising questions over whether more rapid and forceful stimulus may be needed.

Analysts believe the revamped loan prime rate (LPR), which debuts on Tuesday, will be lower than the current level of 4.31%, but are divided over how much funding costs will come down and how quickly.

While China has pushed plenty of liquidity into the financial system over the past year to shore up growth and has guided down short-term rates, loan demand and fresh investment has been relatively subdued amid weakening business confidence and banks' worries of more bad loans.

Under the new mechanism, bank lending rates will be linked to the loan prime rate, which will be linked to the PBOC's medium-term lending facility (MLF) interest rate, and that should establish a relatively smooth policy transmission mechanism, said Ma Jun, a policy adviser to the central bank.

"In the future, if the policy interest rate falls, the loan interest rate will also fall, which will help to reduce the financing cost of enterprises," he said in remarks published on the website of state radio on Monday.

China and Hong Kong stocks rose on expectations the move will ease corporate financing pressures. China's benchmark equity index jumped over 2%, while an index tracking start-ups - potentially the biggest beneficiaries from lower rates - surged 3.5%.

However, some analysts cautioned the reform may not be equivalent to cuts in banks' actual lending rates, as they could still charge higher rates on riskier loans to smaller, private firms while giving state firms better terms.

Still, Chinese banking shares far underperformed the broader market amid worries of lower profitability for lenders. Reactions in the bond and the yuan markets were muted.

"The new system itself doesn't guarantee the actual lending rate will be lower," Goldman Sachs said in a report.