Tesla stock was up 20% at $257.13 in late afternoon trading. Shares are on pace for their largest percentage increase since May 9, 2013, when it rose 24.4%, according to Dow Jones Market Data. It is the second-best performer in the S&P 500 today,

Shares in Tesla rose about 9% afterhours following the electric-car maker's report of a surprise increase in net income on stronger revenue. Some of the key numbers in Wednesday's report: Net income was $2.

It's a bit of a mixed quarter for Tesla, but the stock is up more than 7% in the extended session after the earnings are out. Tesla earned $2.17 billion, or 62 cents a share, in the third quarter, compared with $1.