The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F INFORMATION TABLE
OMB APPROVAL
OMB Number: 3235-0006
Estimated average burden
hours per response: 23.8
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER TITLE OF CLASS CUSIP (x$1000) PRN AMT PRN CALL DISCRETION MANAGER SOLE SHARED NONE
3-D SYS CORP DEL COM NEW COM 88554D205 5,509 633,960 SH   SOLE   633,960 0 0
3M CO COM COM 88579Y101 652 4,325 SH   SOLE   4,325 0 0
AAC HLDGS INC COM COM 000307108 16,559 868,785 SH   SOLE   868,785 0 0
ABBOTT LABS COM COM 002824100 522 11,622 SH   SOLE   11,622 0 0
ABBVIE INC COM COM 00287Y109 525 8,855 SH   SOLE   8,855 0 0
ALPHABET INC- CLASS C COM 02079k107 75,065 98,916 SH   SOLE   98,916 0 0
ALPHABET INC - CLASS A COM 38259P508 230 296 SH   SOLE   296 0 0
AMAZON COM INC COM COM 023135106 560 829 SH   SOLE   829 0 0
AMERICAN TOWER CORP NEW COM COM 03027X100 81,269 838,260 SH   SOLE   838,260 0 0
AMGEN INC COM COM 031162100 289 1,783 SH   SOLE   1,783 0 0
ANSYS INC COM COM 03662Q105 171,009 1,848,745 SH   SOLE   1,848,745 0 0
APPLE INC COM COM 037833100 1,007 9,565 SH   SOLE   9,565 0 0
APPLIED MINERALS INC COM COM 03823M100 23 80,000 SH   SOLE   80,000 0 0
ATRION CORP COM COM 049904105 4,049 10,621 SH   SOLE   10,621 0 0
AUTOMATIC DATA PROCESSING INC COM 053015103 1,890 22,306 SH   SOLE   22,306 0 0
BECTON DICKINSON & CO COM COM 075887109 268 1,741 SH   SOLE   1,741 0 0
BERKLEY W R CORP COM COM 084423102 2,898 52,928 SH   SOLE   52,928 0 0
BERKSHIRE HATHAWAY INC DEL CL COM 084670108 1,385 7 SH   SOLE   7 0 0
BERKSHIRE HATHAWAY INC DEL CL COM 084670702 3,054 23,132 SH   SOLE   23,132 0 0
BIO TECHNE CORP COM COM 09073M104 18,225 202,505 SH   SOLE   202,505 0 0
BIOGEN INC COM COM 09062X103 35,760 116,729 SH   SOLE   116,729 0 0
BLACKBAUD INC COM COM 09227Q100 45,793 695,302 SH   SOLE   695,302 0 0
CAMPBELL SOUP CO COM COM 134429109 226 4,300 SH   SOLE   4,300 0 0
CANADIAN NATL RY CO COM COM 136375102 1,118 20,000 SH   SOLE   20,000 0 0
CAPITAL ONE FINL CORP COM COM 14040H105 1,852 25,662 SH   SOLE   25,662 0 0
CARE CAPITAL PROPERTIES COM 141624106 274 8,961 SH   SOLE   8,961 0 0
CARMAX INC COM COM 143130102 98,087 1,817,442 SH   SOLE   1,817,442 0 0
CELGENE CORP COM COM 151020104 77,438 646,609 SH   SOLE   646,609 0 0
CHEVRON CORP NEW COM COM 166764100 859 9,546 SH   SOLE   9,546 0 0
CHIPOTLE MEXICAN GRILL INC COM COM 169656105 20,251 42,203 SH   SOLE   42,203 0 0
CHUBB LIMITED COM h1467j104 207 1,558 SH   SOLE   1,558 0 0
CISCO SYS INC COM COM 17275R102 1,916 70,571 SH   SOLE   70,571 0 0
COCA COLA CO COM COM 191216100 1,212 28,214 SH   SOLE   28,214 0 0
COGNIZANT TECHNOLOGY SOLUTIONS COM 192446102 240 4,000 SH   SOLE   4,000 0 0
COLGATE PALMOLIVE CO COM COM 194162103 670 10,055 SH   SOLE   10,055 0 0
COMCAST CORP NEW CL A COM 20030N101 3,856 68,335 SH   SOLE   68,335 0 0
CONCHO RES INC COM COM 20605P101 384 4,130 SH   SOLE   4,130 0 0
CORE LABORATORIES N V COM COM N22717107 2,591 23,830 SH   SOLE   23,830 0 0
COSTAR GROUP INC COM COM 22160N109 82,485 399,075 SH   SOLE   399,075 0 0
CROWN CASTLE INTL CORP NEW COM COM 22822V101 5,994 69,333 SH   SOLE   69,333 0 0
DEALERTRACK TECHNOLOGIES INC C COM 242309102 632 10,000 SH   SOLE   10,000 0 0
DENTSPLY INTL INC NEW COM COM 249030107 286 4,700 SH   SOLE   4,700 0 0
DISCOVER FINL SVCS COM COM 254709108 73,851 1,377,294 SH   SOLE   1,377,294 0 0
DISNEY WALT CO COM DISNEY COM 254687106 1,018 9,684 SH   SOLE   9,684 0 0
DONALDSON INC COM COM 257651109 225 7,850 SH   SOLE   7,850 0 0
DOUGLAS DYNAMICS INC COM COM 25960R105 998 47,343 SH   SOLE   47,343 0 0
DU PONT E I DE NEMOURS & CO CO COM 263534109 321 4,815 SH   SOLE   4,815 0 0
DUKE REALTY CORP COM NEW COM 264411505 310 14,750 SH   SOLE   14,750 0 0
DULUTH HOLDINGS INC COM 26443v101 821 56,279 SH   SOLE   56,279 0 0
EAST WEST BANCORP INC COM COM 27579R104 353 8,500 SH   SOLE   8,500 0 0
ECOLAB INC COM COM 278865100 119,783 1,047,236 SH   SOLE   1,047,236 0 0
ELLIE MAE INC COM COM 28849P100 3,305 54,872 SH   SOLE   54,872 0 0
EMERSON ELEC CO COM COM 291011104 475 9,939 SH   SOLE   9,939 0 0
ENTERPRISE PRODS PARTNERS L P COM 293792107 493 19,275 SH   SOLE   19,275 0 0
ENVESTNET INC COM COM 29404K106 56,674 1,898,641 SH   SOLE   1,898,641 0 0
EQT CORP COM COM 26884L109 1,077 20,668 SH   SOLE   20,668 0 0
EQUITY RESIDENTIAL SH BEN INT COM 29476L107 545 6,676 SH   SOLE   6,676 0 0
EXAMWORKS GROUP INC COM COM 30066A105 57,898 2,176,609 SH   SOLE   2,176,609 0 0
EXPONENT INC COM COM 30214U102 32,276 646,158 SH   SOLE   646,158 0 0
EXPRESS SCRIPTS HLDG CO COM COM 30219G108 1,589 18,176 SH   SOLE   18,176 0 0
EXXON MOBIL CORP COM COM 30231G102 1,715 22,002 SH   SOLE   22,002 0 0
FASTENAL CO COM COM 311900104 105,800 2,591,876 SH   SOLE   2,591,876 0 0
FINANCIAL ENGINES INC COM COM 317485100 30,871 916,856 SH   SOLE   916,856 0 0
FISERV INC COM COM 337738108 6,125 66,968 SH   SOLE   66,968 0 0
FORTINET INC COM COM 34959E109 961 30,830 SH   SOLE   30,830 0 0
FREEPORT-MCMORAN INC CL B COM 35671D857 84 12,412 SH   SOLE   12,412 0 0
GENERAL ELECTRIC CO COM COM 369604103 3,946 126,680 SH   SOLE   126,680 0 0
GENUINE PARTS CO COM COM 372460105 424 4,934 SH   SOLE   4,934 0 0
GOOD TIMES RESTAURANTS INC COM COM 382140879 133 27,804 SH   SOLE   27,804 0 0
GUIDEWIRE SOFTWARE INC COM COM 40171V100 484 8,039 SH   SOLE   8,039 0 0
HCP INC COM COM 40414L109 3,609 94,382 SH   SOLE   94,382 0 0
HEALTHCARE SVCS GRP INC COM COM 421906108 70,548 2,023,170 SH   SOLE   2,023,170 0 0
HOME DEPOT INC COM COM 437076102 428 3,233 SH   SOLE   3,233 0 0
IDEXX LABS INC COM COM 45168D104 8,771 120,278 SH   SOLE   120,278 0 0
ILLINOIS TOOL WKS INC COM COM 452308109 208 2,240 SH   SOLE   2,240 0 0
ILLUMINA INC COM COM 452327109 17,279 90,023 SH   SOLE   90,023 0 0
IMAX CORP COM COM 45245E109 118,121 3,323,595 SH   SOLE   3,323,595 0 0
INTEL CORP COM COM 458140100 13,656 396,399 SH   SOLE   396,399 0 0
INTERNATIONAL BUSINESS MACHS C COM 459200101 1,397 10,152 SH   SOLE   10,152 0 0
INTUITIVE SURGICAL INC COM NEW COM 46120E602 101,973 186,709 SH   SOLE   186,709 0 0
INVENTURE FOODS INC COM COM 461212102 246 34,648 SH   SOLE   34,648 0 0
JOHNSON & JOHNSON COM COM 478160104 10,238 99,670 SH   SOLE   99,670 0 0
JPMORGAN CHASE & CO COM COM 46625H100 374 5,671 SH   SOLE   5,671 0 0
KIMBERLY CLARK CORP COM COM 494368103 321 2,523 SH   SOLE   2,523 0 0
LABORATORY CORP AMER HLDGS COM COM 50540R409 2,306 18,653 SH   SOLE   18,653 0 0
LILLY ELI & CO COM COM 532457108 621 7,368 SH   SOLE   7,368 0 0
LINCOLN NATL CORP IND COM COM 534187109 266 5,295 SH   SOLE   5,295 0 0
LITTELFUSE INC COM COM 537008104 214 2,001 SH   SOLE   2,001 0 0
LKQ CORP COM COM 501889208 154,700 5,221,053 SH   SOLE   5,221,053 0 0
LOWES COS INC COM COM 548661107 235 3,089 SH   SOLE   3,089 0 0
LYNAS CORPORATION LTD SHS COM Q5683J103 5 75,000 SH   SOLE   75,000 0 0
M & T BK CORP COM COM 55261F104 494 4,074 SH   SOLE   4,074 0 0
MAGELLAN MIDSTREAM PRTNRS LP C COM 559080106 245 3,600 SH   SOLE   3,600 0 0
MARKEL CORP COM COM 570535104 106,937 121,059 SH   SOLE   121,059 0 0
MASTERCARD INC CL A COM 57636Q104 58,506 600,929 SH   SOLE   600,929 0 0
MCBC HLDGS INC COM COM 55276F107 170 12,434 SH   SOLE   12,434 0 0
MCCORMICK & CO INC COM NON VTG COM 579780206 1,027 12,000 SH   SOLE   12,000 0 0
MCGRAW HILL FINL INC COM COM 580645109 67,765 687,411 SH   SOLE   687,411 0 0
MERCK & CO INC NEW COM COM 58933Y105 1,288 24,387 SH   SOLE   24,387 0 0
MICROSOFT CORP COM COM 594918104 3,366 60,671 SH   SOLE   60,671 0 0
MIDDLEBY CORP COM COM 596278101 1,319 12,230 SH   SOLE   12,230 0 0
MONRO MUFFLER BRAKE INC COM COM 610236101 808 12,203 SH   SOLE   12,203 0 0
MOODYS CORP COM COM 615369105 130,842 1,303,985 SH   SOLE   1,303,985 0 0
NASPERS LTD ADR COM 631512100 339 2,480 SH   SOLE   2,480 0 0
NATIONAL AMERN UNIV HLDGS INC COM 63245Q105 31 15,000 SH   SOLE   15,000 0 0
NEOGEN CORP COM COM 640491106 554 9,800 SH   SOLE   9,800 0 0
NOVARTIS A G SPONSORED ADR COM 66987V109 231 2,688 SH   SOLE   2,688 0 0
O REILLY AUTOMOTIVE INC NEW CO COM 67103H107 18,254 72,032 SH   SOLE   72,032 0 0
ONEBEACON INSURANCE GROUP LTD COM G67742109 515 41,539 SH   SOLE   41,539 0 0
OXYSURE SYSTEMS INC COM COM 69208T101 2 10,000 SH   SOLE   10,000 0 0
PAYCHEX INC COM COM 704326107 3,290 62,200 SH   SOLE   62,200 0 0
PEPSICO INC COM COM 713448108 600 6,007 SH   SOLE   6,007 0 0
PERFORMANCE SPORTS GROUP LTD C COM 71377G100 257 26,730 SH   SOLE   26,730 0 0
PFIZER INC COM COM 717081103 1,077 33,373 SH   SOLE   33,373 0 0
PHILIP MORRIS INTL INC COM COM 718172109 312 3,546 SH   SOLE   3,546 0 0
PINNACLE WEST CAP CORP COM COM 723484101 320 4,956 SH   SOLE   4,956 0 0
PNC FINL SVCS GROUP INC COM COM 693475105 2,484 26,062 SH   SOLE   26,062 0 0
POOL CORPORATION COM COM 73278L105 258 3,188 SH   SOLE   3,188 0 0
POTASH CORP SASK INC COM COM 73755L107 8,976 524,319 SH   SOLE   524,319 0 0
PRA GROUP INC COM COM 69354N106 60,317 1,738,730 SH   SOLE   1,738,730 0 0
PRECISION CASTPARTS CORP COM COM 740189105 394 1,700 SH   SOLE   1,700 0 0
PRICE T ROWE GROUP INC COM COM 74144T108 11,583 162,029 SH   SOLE   162,029 0 0
PROCTER & GAMBLE CO COM COM 742718109 18,273 230,107 SH   SOLE   230,107 0 0
QUALCOMM INC COM COM 747525103 36,530 730,826 SH   SOLE   730,826 0 0
QUALYS INC COM COM 74758T303 7,889 238,411 SH   SOLE   238,411 0 0
RANGE RES CORP COM COM 75281A109 10,754 436,983 SH   SOLE   436,983 0 0
RED HAT INC COM COM 756577102 157,210 1,898,448 SH   SOLE   1,898,448 0 0
ROPER TECHNOLOGIES INC COM 776696106 105,930 558,145 SH   SOLE   558,145 0 0
RUSH ENTERPRISES INC CL A COM 781846209 412 18,817 SH   SOLE   18,817 0 0
SBA COMMUNICATIONS CORP COM COM 78388J106 7,717 73,450 SH   SOLE   73,450 0 0
SCHLUMBERGER LTD COM COM 806857108 14,428 206,855 SH   SOLE   206,855 0 0
SEI INVESTMENTS CO COM COM 784117103 138,019 2,633,959 SH   SOLE   2,633,959 0 0
SIGNET JEWELERS LIMITED SHS COM G81276100 88,045 711,819 SH   SOLE   711,819 0 0
SILVER WHEATON CORP COM COM 828336107 186 15,000 SH   SOLE   15,000 0 0
SMITH & NEPHEW PLC SPDN ADR NE COM 83175M205 392 11,000 SH   SOLE   11,000 0 0
SOTHERLY HOTELS INC COM COM 83600C103 72 11,625 SH   SOLE   11,625 0 0
STERICYCLE INC COM COM 858912108 112,235 930,638 SH   SOLE   930,638 0 0
TANGOE INC COM COM 87582Y108 815 97,131 SH   SOLE   97,131 0 0
TELADOC INC COM 87918A105 845 47,060 SH   SOLE   47,060 0 0
TESLA MTRS INC COM COM 88160R101 238 993 SH   SOLE   993 0 0
TRANSDIGM GROUP INC COM COM 893641100 63,512 278,013 SH   SOLE   278,013 0 0
TRIMBLE NAVIGATION LTD COM COM 896239100 67,016 3,124,266 SH   SOLE   3,124,266 0 0
TYLER TECHNOLOGIES INC COM COM 902252105 43,550 249,829 SH   SOLE   249,829 0 0
ULTIMATE SOFTWARE GROUP INC CO COM 90385D107 383 1,957 SH   SOLE   1,957 0 0
UNDER ARMOUR INC CL A COM 904311107 564 7,000 SH   SOLE   7,000 0 0
UNITED PARCEL SERVICE INC CL B COM 911312106 225 2,342 SH   SOLE   2,342 0 0
UNITED TECHNOLOGIES CORP COM COM 913017109 451 4,690 SH   SOLE   4,690 0 0
US BANCORP DEL COM NEW COM 902973304 1,387 32,507 SH   SOLE   32,507 0 0
V F CORP COM COM 918204108 252 4,054 SH   SOLE   4,054 0 0
VENTAS INC COM COM 92276F100 2,073 36,742 SH   SOLE   36,742 0 0
VERISK ANALYTICS INC CL A COM 92345Y106 100,999 1,313,719 SH   SOLE   1,313,719 0 0
VERIZON COMMUNICATIONS INC COM COM 92343V104 333 7,197 SH   SOLE   7,197 0 0
VISA INC COM CL A COM 92826C839 133,387 1,720,019 SH   SOLE   1,720,019 0 0
W P CAREY INC COM COM 92936U109 334 5,654 SH   SOLE   5,654 0 0
WAGEWORKS INC COM COM 930427109 98,525 2,171,589 SH   SOLE   2,171,589 0 0
WASTE CONNECTIONS INC COM COM 941053100 86,285 1,532,044 SH   SOLE   1,532,044 0 0
WATSCO INC COM COM 942622200 785 6,700 SH   SOLE   6,700 0 0
WELLS FARGO & CO NEW COM COM 949746101 352 6,472 SH   SOLE   6,472 0 0
WELLTOWER INC COM 95040q104 328 4,826 SH   SOLE   4,826 0 0
WHOLE FOODS MKT INC COM COM 966837106 529 15,800 SH   SOLE   15,800 0 0
WSFS FINL CORP COM COM 929328102 826 25,517 SH   SOLE   25,517 0 0
ZOES KITCHEN INC COM COM 98979J109 295 10,553 SH   SOLE   10,553 0 0
BLACKROCK ENHANCED EQT DIV TR ETFS 09251A104 76 10,000 SH   SOLE   10,000 0 0
VANGUARD FTSE ALL WORLD EX US ETFS 922042775 2,634 60,681 SH   SOLE   60,681 0 0
VANGUARD INDEX FDS REIT ETF ETFS 922908553 680 8,530 SH   SOLE   8,530 0 0
VANGUARD INTL EQUITY INDEX FD ETFS 922042858 423 12,925 SH   SOLE   12,925 0 0
VANGUARD SHORT TERM GOVT ETF ETFS 92206c102 439 7,225 SH   SOLE   7,225 0 0
VANGUARD SPECIALIZED PORTFOLIO ETFS 921908844 976 12,555 SH   SOLE   12,555 0 0
VANGUARD WHITEHALL FDS INC HIG ETFS 921946406 380 5,700 SH   SOLE   5,700 0 0