• A key measure the Federal Reserve watches closely showed inflation during May slowed to its lowest annual rate in more than three years.
• Home prices might finally be starting to cool down.
• President Joe Biden and former President Donald Trump faced off in their first debate of the 2024 presidential campaign.

Here are five key things investors need to know to start the trading day:

1. Watching and waiting

The S&P 500 closed little changed on Thursday, ending the day just 0.09% higher, as investors wait for fresh inflation data (more on that below). The Nasdaq Composite, meanwhile, rose 0.30%, while the Dow Jones Industrial Average added only 36.26 points, or 0.09%. Key semiconductor stocks fell for the day, as Micron shares dropped more than 7% and market bellwether Nvidia dipped 1.9%. Follow live market updates.

2. Big inflation reading

Inflation during May slowed to its lowest annual rate in more than three years, according to an important economic measure for the Federal Reserve that was released Friday morning. The core personal consumption expenditures price index, which excludes volatile food and energy, increased just a seasonally adjusted 0.1% for the month and was up 2.6% from a year ago, according to a Commerce Department report. The annual level was down 0.2 percentage point from the April level. Both were in line with Dow Jones estimates.

3. Cooling off

Summer is in full swing, but home prices might finally start to cool down. Several reports show that price gains are shrinking and home sellers are starting to give a bit on pricing. The typical house sold for slightly less than its asking price — 0.3% lower — for the first time since the start of the Covid-19 pandemic during the four weeks ended June 23, according to real estate brokerage Redfin. Supply is also starting to grow, with active listings now 35% higher than they were at this time a year ago, after a huge drop in inventory. But even still, home prices are 47% higher than they were in early 2020, and the median sale price is five times the median household income.

4. Walgreens wanes

Shares of Walgreens plunged 22% on Thursday after the company reported earnings that fell short of expectations and slashed its full-year adjusted profit outlook. The retail pharmacy giant said it was facing a "challenging" environment. ″'We assumed ... in the second half that the consumer would get somewhat stronger" but "that is not the case," CEO Tim Wentworth told CNBC. The results come as Walgreens works to simplify its U.S. healthcare portfolio and slash costs by closing underperforming U.S. stores, among other things.

5. Up for debate

President Joe Biden and former President Donald Trump faced off in their first debate of the 2024 presidential campaign on Thursday. The two argued for 90 minutes and touched on topics including the economy, concerns about their ages, abortion and more. The debate came as Trump faces two criminal prosecutions over his efforts to overturn his loss in the 2020 election to Biden. But Biden's campaign faced hard questions after the event wrapped, and worried Democratic campaign donors and fundraisers started to express concerns about his disappointing performance less than 20 minutes into the debate.

— CNBC's Hakyung Kim, Jeff Cox, Diana Olick, Annika Kim Constantino, Dan Mangan, Kevin Breuninger, Christina Wilkie, Brian Schwartz, Rebecca Picciotto and Josephine Rozzelle contributed to this report.

— Follow broader market action like a pro on CNBC Pro.