If you are looking for clues telling you which stocks have a good chance of increasing in value, you might want consider watching what insiders are doing. After all, talk is cheap, but when insiders put their own money on the line, you should sit up and take note.

Take-Two Interactive Software Inc (TTWO) topped the insider-buying charts for the week ending July 9 as insiders snapped up 427,900 shares of company stock at a market value of $4,093,939. During the past six months, insiders have increased their overall holdings in the company by 64.15% and now own 2.74% of TTWO stock.

If you are looking for clues telling you which stocks have a good chance of increasing in value, you might want consider watching what insiders are doing. After all, talk is cheap, but when insiders put their own money on the line, you should sit up and take note.

Trius Therapeutics Inc (TSRX) topped the insider-buying charts for the week ending July 9th as insiders snapped up 3,001,859 shares of company stock at a market value of $15,009,295. During the past six months, insiders have increased their overall holdings in the company by 354.34% and now own 57.55% of TSRX stock.

Medicines Co (MDCO) was not far behind, with insiders buying 667,040 shares at a market value of $8,037,832. Insiders now own 1.43% of the company's stock after decreasing their overall holdings by -4.17% during the past six months.

Medicines Co (NASDAQ: MDCO) volatility spikes on hope for patent extension and 7/25 EPS.

• MDCO is a developer of products to improve acute hospital care and Angiomax; a treatment to clear restricted blood vessels near the heart.
  
• MDCO will announce EPS on July 25th.
  
• RBC Capital says: "It appears that an amendment to the Senate version of the pending Patent Reform Act contains language granting the USPTO discretion to accept late filings for patent extension. This gives MDCO a potential path to gaining patent extension beyond its 2010 expiration."
  
• MDCO August option implied volatility of 78 is above its 26-week average of 43 according to Track Data, suggesting larger price fluctuations.

Caterpillar (NYSE: CAT) volatility elevated after EPS of $1.24.

• CAT reported second-quarter sales and revenues of $11.3 billion and a profit of $823 million.
  
• Smith Barney says: "Overall, stock is going to get hit hard today as earnings power is back to 'believe me' story about operational performance."
  
• CAT overall option implied volatility of 30 is above its 26-week average of 25 according to Track Data, suggesting larger risk.

Daily Option Update is provided by Stock Options Specialist Paul Foster of theflyonthewall.com.