US Markets

Stock futures fluctuate; Wells Fargo reports

U.S. stock-index futures wavered on Friday, little changed after a bumpy day which saw concerns over Portugal's banking sector travel across the Atlantic.

Wells Fargo posted quarterly earnings that met expectations, while revenue exceeded Wall Street estimates.

Shares of the bank dipped following the report.

Stock market volatility could remain elevated

Other big banks - like JPMorgan, Citigroup and Bank of America - are expected to show steep earnings declines.

Read MoreHere's what's happening in Portugal

It comes after a slump in global markets, sparked by concerns about the financial stability of troubled Portuguese lender Banco Espirito Santo (BES). Trading in BES was suspended and a late-night press release hoped to cool fears ahead of Friday's market open with shares once again being suspended in morning trade.

U.S. stocks retained sizable losses on Thursday, but recouped more than half of the steep dive. The Dow Jones Industrial Index recovered to close 70.54 points lower, after losing 180 points earlier in the day.

Read MorePortugal's BES hitsback–should we blame the parent?

"The ongoing AQR (asset quality review) and stress tests are likely to reveal banks that require additional capital and this missed debt payment by an entity within Espirito Santo Financial Group underlines the need for a credible stress testing process to be completed as soon as possible," Bank of Tokyo-Mitsubishi's Derek Halpenny said in a morning note, but added that the episode may not escalate.

"Events in Portugal will be watched closely today, but the released statement last night providing clarity of exposures should help alleviate further investor selling today."

In Europe, shares were stable on Friday, as traders digested the BES release.

The U.S. Treasury is due to release its monthly budget statement Friday, but beyond that no major data releases are expected. Atlanta Fed President Dennis Lockhart and Chicago Fed President Charles Evans will be speak on the economy later in the day.