The Dow Jones industrial average slipped 5.23 points to 16,995.13.
The S&P 500 gained 0.31 points to 1,989.57, while the tech-focused Nasdaq index fell 12.22 points to 4,662.16.
US markets mirrored those in Europe after ECB head Mario Draghi said the bank would expand stimulus measures, but did not expect further rate cuts.
Shares in mobile payment company Square fell 6.1%. The company reported on Wednesday that it had seen growth in payment volume over the fourth quarter, but also increasing operating expenses.
Dollar General shares rose 10.7% after the company reported profits of $376m. Its discount competitor Dollar Tree saw its share price rise 4%.

Roedd Jason Cooper wedi bod o flaen llys o'r blaen ar gyhuddiad o geisio llofruddio Laura Jayne Stuart, ond clywodd y llys ddydd Gwener bod Ms Stuart wedi marw.
Ymddangosodd Mr Cooper, 27 oed o Ddinbych, ar gyswllt fideo o garchar Altcourse yn Lerpwl.
Mae'n wynebu cyhuddiadau o lofruddio Ms Stuart yn Ninbych ar 12 Awst, ac o glwyfo David Roberts gyda'r bwriad o achosi niwed corfforol difrifol iddo.
Doedd dim cais am fechnïaeth ac fe gafodd y diffynnydd ei gadw yn y ddalfa nes i'r achos yn ei erbyn ddechrau ym mis Chwefror, 2018.
Er bod dyn wedi ei gyhuddo, mae Heddlu Gogledd Cymru yn pwysleisio fod eu hymchwiliad yn parhau, a bod swyddogion yn dal i chwilio am y gyllell gafodd ei defnyddio i drywanu Ms Stuart.
Mae'r heddlu yn gofyn i unrhyw un sydd â gwybodaeth i gysylltu drwy ffonio 101 neu 0800 555 111 gan ddefnyddio'r cyfeirnod RC 1712 2068.

Unicode, the authority on computer text and characters, has already approved adding the three flags to the next release of emojis in June.
Technology companies such as Apple, Google, Microsoft and Facebook will be able to introduce the flags to their software from July.
A UK flag is already available on smartphones and other devices.
Unicode develops the mechanism for making the flags available, but manufacturers have to add the new emojis to their keyboards.
Emoji flags already available include those for Ascension Island, St Barthelemy, Curacao, Diego Garcia and Djibouti.
The campaign for a new range of emoji flags was started by Jeremy Burge of Emojipedia and BBC Wales' social media lead Owen Williams in March 2016.
(Close): US stocks finished mostly lower following a turbulent trading day and an announcement of new stimulus from the European Central Bank.
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Mae dyn wedi ymddangos o flaen Llys y Goron Yr Wyddgrug i wynebu cyhuddiad o lofruddiaeth.
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Emoji flags for Wales, Scotland and England could be available on tablets and smartphones by the summer.