U.S. stock index futures were little changed on yesterday as investors digested the possibility of an interest rate hike in the coming months and awaited data for clues regarding the strength of the economy.

Federal Reserve Chair Janet Yellen on Friday pointed at improvement in the economy and a strong labor market, and she said a rate hike in the coming months would likely be appropriate.

Yellen’s comments come after months of uncertainty on the Fed’s stance on rates swayed the markets, especially worrying investors after the first quarter started on a weak note.

Her comments helped Wall Street close higher on Friday, capping off its strongest week since March. The benchmark S&P 500 index .SPX has risen about 1.6 per cent in May and is set to record its third straight month of gains. U.S. markets were closed on Monday for the Memorial Day holiday.

Traders raised their expectations of a rate hike in June to 28 percent after Yellen’s speech, from just over four per cent at the start of May, according to CME Group’s FedWatch tool.

St. Louis Fed President James Bullard said on Monday that global markets appear to be “well-prepared” for a summer rate hike, although he did not specify a date for the policy move. The Fed next meets on June 14 and 15.

Data due yesterday is expected to show consumer spending, the Fed’s preferred measure of inflation, likely rose 0.2 per cent in April, compared with a 0.1 per cent increase in March. The Fed’s inflation rate target is two per cent.

Separately, a report from the Conference Board on consumer confidence is expected to show the index at 96.0 in May, up from a reading of 94.2 in the previous month.

Celator Pharma jumped by 73.2 per cent to $30.37 premarket after agreeing to be bought by Jazz Pharma for about $1.5 billion. Jazz Pharma was untraded.

Utility Westar Energy was up nearly nine per cent at $57.65 after agreeing to be bought by Great Plains for $8.6 billion. Great Plains was untraded pre-market.