Welcome to edition 188 of Insider Weekends. Insider buying increased last week with insiders purchasing $78.41 million of their stock compared to $17.78 million in the week prior. Selling decreased with insiders selling $575.8 million of stock last week compared to $831.24 million in the week prior.

Sell/Buy Ratio: The insider Sell/Buy ratio is calculated by dividing the total insider sales in a given week by total insider purchases that week. The adjusted ratio for last week decreased to 7.34. In other words, insiders sold more than 7 times as much stock as they purchased. The Sell/Buy ratio this week compares favorably with the prior week, when the ratio stood at 46.76. We are calculating an adjusted ratio by removing transactions by funds and companies and trying as best as possible only to retain information about insiders and 10% owners who are not funds or companies.

Insider Sell Buy Ratio January 24, 2014

Note: As mentioned in the first post in this series, certain industries have their preferred metrics such as same store sales for retailers, funds from operations (FFO) for REITs and revenue per available room (RevPAR) for hotels that provide a better basis for comparison than simple valuation metrics. However metrics like Price/Earnings, Price/Sales and Enterprise Value/EBITDA included below should provide a good starting point for analyzing the majority of stocks.

Notable Insider Buys:

Some of the insider purchases that did not make the top 5 list but are worth exploring include additional purchases of Tessera Technologies (TSRA) by the value oriented activist hedge fund Starboard Value and a couple of small purchases by the CFO and a director of the campus apartments REIT American Campus Communities (ACC).

1. Opko Health, Inc. (OPK): $8.46

CEO & Chairman Phillip Frost M.D. acquired 80,600 shares of this medical devices and drug development company, paying $8.80 per share for a total amount of $709,322. These shares were purchased indirectly by Frost Gamma Investments Trust.

You can view the list of recent insider transactions for Opko Health, Inc. here.