American Express' (AXP) reaffirmation of full-year guidance and positive billing trends will likely be the driver of the company's shares in Q2, BofA Securities said in a Thursday note.

Based on conversations with investors, BofA analysts said that billed business growth is expected to grow 7% to 8%, up from 4.9% in Q1, based on resilient consumer spending, easier year-over-year comparisons and more favorable foreign exchange rates.

If the billings growth is sustainable, the reaffirmation of revenue growth in the range of 8% to 10% could "provide additional upside" to the stock, the analysts said.

Valuations of the company's stock were also above historical averages, with sentiment "notably strong," the analysts said.

The analysts had the same Q2 projection as the consensus at $3.88 per share.

BofA reiterated its buy rating on the stock, with a price target of $353.

Price: 323.09, Change: +5.74, Percent Change: +1.81