There were 18 notable investor filings today. Carbo Ceramics Inc. (NYSE:CRR) is the largest company of interest.

When a person or group of persons acquires beneficial ownership of more than 5% of a company’s equity securities, they are required to file a Schedule 13D or 13G with the SEC. If these groups intend to influence management into changing the business strategy, they are considered “activist” investors. There is considerable academic research that suggest activist investors contribute to excess returns in equities in the subsequent twelve months after the event.

Investors that acquire 10% or more of a company’s shares, or that gain a board seat, are considered insiders by the SEC and are subject to stricter insider trading filing requirements.

New Passive Investor Filings

Investors that acquire more than 5% of the shares of a company but have no intention of influencing management are considered passive investors and must file a 13G.

Babcock & Wilcox Enterprises Inc. (NYSE:BW) – First Pacific Advisors, LLC has filed a new SC 13G, reporting a 10.10% ownership stake in Babcock & Wilcox Enterprises. This is an increase of 24.69% from their previous filing.

Mattersight Corp. (NASDAQ:MATR) – PenderFund Capital Management Ltd. has filed a new SC 13G, reporting a 5.60% ownership stake in Mattersight.

Celadon Group, Inc. (NYSE:CGI) – Wellington Trust Company, National Association Multiple Common Trust Funds Trust, Micro Cap Equity Portfolio has filed a new SC 13G, reporting a 5.20% ownership stake in Celadon Group.

Conyers Park Acquisition Corp. (NASDAQ:CPAA) – WELLINGTON MANAGEMENT GROUP LLP has filed a new SC 13G, reporting a 17.21% ownership stake in Conyers Park Acquisition. This is an increase of 53.39% from their previous filing.

Amended Activist Investor Filings

Taylor Morrison Home Corp. (NYSE:TMHC) – TPG Group Holdings (SBS) Advisors, Inc. has filed an amended Schedule 13D/A, reporting a 32.80% ownership stake in Taylor Morrison Home. This is a decrease of 19.41% from their previous filing.

Amyris, Inc. (NASDAQ:AMRS) – Temasek Holdings (Private) Ltd has filed an amended Schedule 13D/A, reporting a 18.50% ownership stake in Amyris. This is a decrease of 4.64% from their previous filing.

CIBER, Inc. (NYSE:CBR) – Lone Star Value Management LLC has filed an amended Schedule 13D/A, reporting a 2.20% ownership stake in CIBER. This is a decrease of 47.99% from their previous filing.

Carbo Ceramics Inc. (NYSE:CRR) – Wilks Brothers, LLC has filed an amended Schedule 13D/A, reporting a 11.30% ownership stake in Carbo Ceramics. This is an increase of 18.95% from their previous filing.

Amended Passive Investor Filings

Enbridge Energy Management LLC. (NYSE:EEQ) – MORGAN STANLEY has filed an amended Schedule 13D/A, reporting a 1.00% ownership stake in Enbridge Energy Management. This is a decrease of 84.85% from their previous filing.

Zogenix, Inc. (NASDAQ:ZGNX) – PERCEPTIVE ADVISORS LLC has filed an amended Schedule 13D/A, reporting a 13.89% ownership stake in Zogenix. This is an increase of 168.15% from their previous filing.

OSI Systems, Inc. (NASDAQ:OSIS) – EARNEST PARTNERS LLC has filed an amended Schedule 13D/A, reporting a 5.10% ownership stake in OSI Systems. This is an increase of 2.00% from their previous filing.

Streamline Health Solutions, Inc. (NASDAQ:STRM) – AWM Investment Company, Inc. has filed an amended Schedule 13D/A, reporting a 1.90% ownership stake in Streamline Health Solutions. This is a decrease of 66.67% from their previous filing.

Innoviva, Inc. (NASDAQ:INVA) – BAUPOST GROUP LLC/MA has filed an amended Schedule 13D/A, reporting a 0.92% ownership stake in Innoviva. This is a decrease of 94.08% from their previous filing.

The Madison Square Garden Company New (NYSE:MSG) – LAZARD ASSET MANAGEMENT LLC has filed an amended Schedule 13D/A, reporting a 6.90% ownership stake in Madison Square Garden. This is a decrease of 42.26% from their previous filing.

iRhythm Technologies, Inc. (NASDAQ:IRTC) – Novo A/S has filed an amended Schedule 13D/A, reporting a 0.00% ownership stake in iRhythm Technologies. This is a decrease of 100.00% from their previous filing.

Envestnet, Inc. (NYSE:ENV) – WELLINGTON MANAGEMENT GROUP LLP has filed an amended Schedule 13D/A, reporting a 1.88% ownership stake in Envestnet. This is a decrease of 80.89% from their previous filing.

Stoneridge, Inc. (NYSE:SRI) – PZENA INVESTMENT MANAGEMENT LLC has filed an amended Schedule 13D/A, reporting a 4.47% ownership stake in Stoneridge. This is a decrease of 20.18% from their previous filing.

Investors Title Co. (NASDAQ:ITIC) – BlackRock Inc. has filed an amended Schedule 13D/A, reporting a 4.90% ownership stake in Investors Title. This is a decrease of 14.04% from their previous filing.

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