Traders and investors were sent reeling after the hot US jobs report at the end of last week. Since then, there is an air of nervousness surrounding equities - not least with the US-Iran conflict continuing to rage on.The trepidation is likely tied to the fact that market players will have to deal with another big US data point later today. That being the US CPI report for the month of May.Headline annual inflation is estimated to climb above 4% for the first time in three years. And that alone might be enough to spook markets, even if core prices are not expected to jump up as much.S&P 500 futures are down 0.4% on the day as tech shares continue to lag. Nasdaq futures are down 0.5% while Dow futures are down 0.3% currently.There was much volatile trading yesterday as well in Wall Street. US stocks opened stronger before reversing sharply lower but managed to recoup a large chunk of the losses before the closing bell. Still, it points to added jitters with one eye also on the SpaceX IPO on 12 June.But for the time being, all eyes are on the US CPI report first and foremost. With the jobs data from last week already jolting markets amid fears of a more hawkish Fed, this could yet be the follow up to that.And that is perhaps reason why we are seeing a further defensive mood in US stocks this week and in the run up to the economic data release later.US May CPI +0.5% m/m expected (Prior +0.6%)US May CPI +4.2% y/y expected (Prior +3.8%)US May core CPI +0.3% m/m expected (Prior +0.4%)US May core CPI +2.9% y/y expected (Prior +2.8%) This article was written by Justin Low at investinglive.com.