Exxon Mobil’s stellar earnings growth in recent years had hardly disappointed its investors. But now, the company whose profit for last year was the largest in corporate history is slipping in its performance.

Exxon Mobil said Thursday that its second-quarter profit tumbled 66 percent, a sign the company was not immune to lower oil prices and weaker demand.

The company reported that its net income fell to $3.95 billion, or 81 cents a share, from $11.68 billion, or $2.22 a share, in the period a year ago.

The results were well below market estimates of $1.02 a share and the weakest for the company since the third quarter of 2003, reflecting lower oil and gas production and losses at the company’s domestic refining business. Exxon’s shares fell 1 percent, or 71 cents, on Thursday to close at $70.72.