The Dow Jones Industrial Average (DJI) is up over 150 points midday, looking to end the volatile week of trading on a high note. The S&P 500 Index (SPX) and Nasdaq Composite (IXIC) are also comfortably in the black, as investors keep an eye on a mixed bag of tech stocks after the sector's recent slump. Despite today's positive price action, all three indexes are on track for steep back-to-back weekly losses. Meanwhile, in economic data, the U.S. consumer price index (CPI) rose for the third straight month. 

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One stock seeing notable options activity is Nikola Corporation (Nasdaq: NKLA), down 14.6% at $32.08 after short-seller Hindenburg yesterday accused the company of fraud. So far, 168,000 puts have crossed the tape -- 14 times what's typically seen at this point. Most popular are the September 30 and 25 puts, with new positions being opened at both. 

Scaling the Nasdaq today is Laureate Education Inc (Nasdaq: LAUR), up 22.3% at $14.88 at last check, after it was announced that the company is selling Walden University to Adtalem Global Education for $1.48 billion. Though still posting an 18.2% year-to-date deficit, the equity is now at levels not seen since mid-March and has toppled its 320-day moving average.

Meanwhile, Spero Therapeutics Inc (Nasdaq: SPRO) is dropping lower, down 8.5% at $10.18, after announcing a public offering of 4.7 million shares of common stock. The recently volatile stock is still up 56.8% in the last six months and has held on to its year-to-date breakeven level today.