Square closed up 5.5% on Monday after Bloomberg News reported the payments company could offer savings and checking accounts in the near future.
The report said a code within a Square app update revealed the company's plans including details about checking and savings accounts.
The hidden code uses rhetoric that leads Bloomberg to believe Square will offer a 0.5% interest rate for its savings account through 2021.
Square did not comment on the report.
The company's shares are down 3% this year and are off more than 25% from their most recent high.
The payments company saw blowout earnings earlier this month. Square reported first-quarter earnings of 41 cents a share, well above the FactSet estimate of 17 cents. Revenue of $5.06 billion also came in above expectations of $3.36 billion.
— With reporting from CNBC's Michael Bloom.