• U.S. President Joe Biden announced his withdrawal from the 2024 presidential race, endorsing Vice President Kamala Harris.
• Traders return to the markets after machines running Microsoft's Windows operating system crashed Friday due to a glitch in an update issued by cybersecurity company CrowdStrike. Shares of CrowdStrike plunged 11% on Friday.
• On Monday, China's central bank unexpectedly cut rates, with the short term 7-day reverse repurchase rate lowered to 1.7% from 1.8%. The one-year and five-year loan prime rates were also trimmed by 10 basis points each to 3.35% and 3.85% respectively,

Asia-Pacific markets fell on Monday, as news emerged that U.S. President Joe Biden had dropped out of the presidential race and endorsed Vice President Kamala Harris as the Democratic nominee.

On Monday, China's central bank unexpectedly cut rates, with the short term 7-day reverse repurchase rate lowered to 1.7% from 1.8%.

The one-year and five-year loan prime rates were also trimmed by 10 basis points each to 3.35% and 3.85% respectively, surprising markets as economists were not expecting any change. The People's Bank of China will also reduce collateral requirements for its medium-term lending facility from July. The current MLF rate stands at 2.5%.

A survey by Reuters last week showed that 64% of all respondents expected both the one-year and five-year LPR to stay unchanged.

The one-year LPR acts as the benchmark for most corporate loans, and the five-year LPR serves as a reference rate for mortgages.

Hong Kong's Hang Seng index was at 1.22% as of its final hour of trade after the PBOC's announcement, while mainland China's CSI 300 lost 0.68% to close at 3,514.92. The offshore Chinese yuan weakened 0.1% to trade at 7.2922 against the greenback.

Elsewhere in Asia, the Indian rupee also hit a record low against the U.S dollar, weakening to as low as 83.6775, surpassing its previous record low of 83.6650 in June.

Investors will also assess the impact of the massive global IT outage late last week. Machines running Microsoft's Windows operating system crashed Friday due to a glitch in an update issued by cybersecurity company CrowdStrike, causing its shares to plunge by 11%.

Microsoft said in a blog post on the weekend it estimated that 8.5 million Windows devices — or less than 1% of all Windows machines — were affected. 

This week, investors will be looking out for GDP data from South Korea and the U.S., as well as factory activity data from around the region. South Korea and the the U.S will announce second-quarter advance GDP numbers on Thursday.

Other economic data this week include inflation numbers from the U.S. and Singapore on Friday and Tuesday, respectively.

The Taiwan Weighted Index led losses in the region, tumbling 2.68% to close at 22,256.99, dragged by industrial and tech stocks.

Japan's Nikkei 225 fell 1.16% to end at 39,599, while the broad-based Topix also was down by the same measure to close at 2,827.53. This was the first time in three weeks that the Nikkei dipped below the 40,000 mark.

South Korea's Kospi dropped 1.14% lower to 2,763.51, while the small-cap Kosdaq saw a larger loss of 2.26% and ended at 809.96.

Australia's S&P/ASX 200 dropped 0.5%, ending the day at 7,931.7.

On Wall Street, all three major indexes retreated on Friday and U.S. stock markets wrapped up the week defined by a rotation out of this year's mega cap winners in favor of smaller names.

The S&P 500 dropped 0.71%, while the tech heavy Nasdaq Composite slid 0.81%. The Dow Jones Industrial Average fell 377.49 points, or 0.93%, to 40,287.53.

— CNBC's Alex Harring and Jesse Pound contributed to this report.

Correction: This story has been updated to correct the U.S. advance GDP release day.