Market value 50

Ranked by market capitalization on March 31, 2011

2011 rank	2010 rank	Company	Market value (billions)	Change (%)
1	1	EMC Corp.	$54,787.2	48.2
2	-	Covidien	25,650.5	2.0
3	2	State Street Corp.	22,568.4	0.6
4	4	Thermo Fisher Scientific	21,698.2	3.0
5	6	American Tower Corp.	20,594.2	20.0
6	9	Genzyme Corp.	20,079.7	45.6
7	5	TJX Cos.	19,377.6	11.3
8	3	Raytheon Co.	18,297.6	-15.5
9	8	Biogen Idec	17,748.8	14.7
10	7	Staples	13,972.0	-18.1
11	11	Boston Properties	13,527.6	29.1
12	12	Analog Devices	11,798.6	37.5
13	10	Boston Scientific Corp.	10,986.5	0.4
14	13	Vertex Pharmaceuticals	9,797.5	19.5
15	14	Waters Corp.	7,936.1	25.6
16	17	Akamai Technologies	7,111.7	31.5
17	16	Iron Mountain	6,252.1	12.1
18	29	Skyworks Solutions	6,043.3	120.4
19	19	Nuance Communications	5,876.2	24.4
20	18	Hologic	5,790.0	20.8
21	22	Affiliated Managers Group	5,677.3	69.7
22	21	NStar	4,793.0	26.7
23	-	Acme Packet	4,668.0	300.4
24	20	Eaton Vance Corp.	3,827.8	-3.3
25	32	Varian Semiconductor Equipment Associates	3,655.6	48.4
26	33	Bruker Corp.	3,445.0	43.0
27	23	Alere	3,341.5	2.3
28	39	Teradyne	3,301.0	66.7
29	27	Senior Housing Properties Trust	3,268.3	15.8
30	37	Cabot Corp.	3,030.5	52.5
31	28	PerkinElmer	2,984.8	6.2
32	26	Hospitality Properties Trust	2,857.7	-3.3
33	-	IPG Photonics Corp.	2,723.4	299.4
34	34	Parametric Technology Corp.	2,656.5	25.6
35	38	BJ's Wholesale Club	2,649.9	33.5
36	41	Clean Harbors	2,604.4	78.6
37	31	VistaPrint Ltd.	2,221.1	-10.8
38	30	Charles River Laboratories International	2,167.6	-16.7
39	35	Novell	2,093.6	0.2
40	36	Hanover Insurance Group	2,047.4	-0.6
41	45	Hittite Microwave Corp.	1,993.0	50.0
42	47	Progress Software Corp.	1,947.8	50.3
43	-	CommonWealth	1,873.5	-5.1
44	-	MKS Instruments	1,728.3	78.1
45	42	Haemonetics Corp.	1,666.0	16.0
46	-	Sapient Corp.	1,568.8	29.0
47	49	athenahealth	1,563.3	25.6
48	46	Cubist Pharmaceuticals	1,500.5	14.5
49	44	Parexel International Corp.	1,459.2	7.8
50	43	Pegasystems	1,415.7	3.9