Although the index closed higher Friday, it slipped nearly 4.8% overall last week. It was Hang Seng's biggest weekly fall since August. The city has been rattled by violent protests that escalated in recent days.
The local economy has also been affected. The Hong Kong government on Friday warned that mass protests could cause the economy to shrink by 1.3% this year, marking the first annual recession since 2009.
There is another sign that the central bank is "starting to take a more proactive approach" to push down borrowing costs to support economic growth, said Julian Evans-Pritchard, senior China economist for Capital Economics.
Monday's move could encourage banks to lower the Loan Prime Rate on Wednesday, as banks' funding costs are lower, he wrote in a research note. LPR is the interest rate that banks require corporate customers for new loans. It is a new lending standard that China introduced in August and hopes to gradually replace the existing fixed reference lending rate.
Elsewhere in the region, markets were relatively subdued. Japan's Nikkei 225 ( N225 ) received 0.3%. However, South Korea's Kospi Index ( KOSPI ) slipped 0.3% .
Investors may be looking for more news about trading. Wall Street's big indices all closed on the green on Friday, partly due to US and China trade optimism. Over the weekend, China's trade ministry said Chinese and US dealers had had a "constructive discussion" about a phase one deal.
SoftBank ( SFTBF ) on Monday announced a plan to merge its unit Z Holdings, formerly Yahoo Japan, with messaging operator Line Corp in 2020.
Z Holdings [1
9659004] ( YAHOY )
and Line Corp ( LN )
were last up 1.2% and 2.2% each in Tokyo.
American futures, meanwhile, receded slightly during Asian trading hours on Monday. Futures for Dow ( INDU ) S&P 500 ( SPX ) and Nasdaq  ( COMP ) were all down.