Pricing Term Sheet dated as
of September 24, 2012

Issuer Free Writing Prospectus
Filed Pursuant to Rule 433

Registration Statement No. 333-184045

Supplementing the Preliminary

Prospectus Supplement

dated September 24, 2012 and the

Prospectus dated September 24, 2012

Issuer:

GT Advanced Technologies Inc. (NASDAQ: GTAT)

Notes:

3.00% Convertible Senior Notes due 2017

Trade Date:

September 25, 2012

Settlement Date:

September 28, 2012

Offering Size:

$205 million ($220 million if the underwriters exercise their option to purchase additional Notes in full)

Maturity:

October 1, 2017, subject to earlier repurchase or conversion

Public Offering Price:

100% of principal amount, plus accrued interest, if any, from the Settlement Date

Underwriting Discounts and Commissions:

3% of principal amount

Interest Rate:

3.00% per annum accruing from the Settlement Date, payable semi-annually in arrears on April 1 and October 1 of each year, beginning on April 1, 2013

NASDAQ Last Reported Sale Price on September 24, 2012:

$5.93 per share of the Issuer’s common stock

Conversion Premium:

Approximately 30% above the NASDAQ Last Reported Sale Price on September 24, 2012

Initial Conversion Rate:

129.7185 shares of the Issuer’s common stock per $1,000 principal amount of Notes

Initial Conversion Price:

Approximately $7.71 per share of the Issuer’s common stock

Use of Proceeds:

The net proceeds from this Offering are estimated to be approximately $198.3 million (or $212.9 million if the underwriters exercise their option to purchase additional Notes in full), after deducting fees and estimated offering expenses payable by the Issuer. The Issuer expects to enter into convertible note hedge transactions with one or more counterparties, one or more of which may be underwriters or affiliates thereof (each of which is referred to as an “option counterparty”). The Issuer also intends to enter into warrant transactions with the option counterparties. The Issuer intends to use approximately $15.2 million of the net proceeds from this Offering to pay the cost of the convertible note hedge transactions (after such cost is partially offset by the proceeds to the Issuer from the sale of the warrant transactions). The Issuer intends to use the remainder of the net

proceeds from this Offering for general corporate purposes, which may include the acquisition of companies or businesses, repayment and refinancing of debt, working capital and capital expenditures.

If the underwriters exercise their option to purchase additional Notes, the Issuer may sell additional warrants and use a portion of the net proceeds from the sale of the additional Notes, together with the proceeds from the additional warrants, to enter into additional convertible note hedge transactions and for general corporate purposes as described above.

Adjustment to Shares Delivered upon Conversion in connection with a Make-Whole Fundamental Change:

The following table sets forth the hypothetical stock price and the number of additional shares to be received per $1,000 principal amount of Notes upon conversion in connection with a make-whole fundamental change for each stock price and the effective date set forth below. The stock prices set forth in the first row of the table below, and the number of additional shares, are subject to adjustment as described in the Preliminary Prospectus Supplement.

Effective Date

$5.93

$6.50

$7.00

$7.50

$8.00

$8.50

$9.00

$10.00

$11.00

$12.00

$13.00

$14.00

$15.00

$20.00

$25.00

$30.00

September 28, 2012

38.9155

37.8374

32.9196

28.8807

25.5279

22.7178

20.3418

16.5776

13.7663

11.6143

9.9314

8.5903

7.5037

4.2411

2.6663

1.7657

October 1, 2013

38.9155

36.3213

31.2204

27.0710

23.6610

20.8324

18.4659

14.7747

12.0757

10.0514

8.4987

7.2832

6.3141

3.4995

2.1898

1.4482

October 1, 2014

38.9155

34.3716

29.0250

24.7320

21.2530

18.4096

16.0671

12.4968

9.9685

8.1312

6.7635

5.7222

4.9126

2.6730

1.6776

1.1147

October 1, 2015

38.9155

31.7801

26.0630

21.5609

17.9920

15.1447

12.8588

9.5103

7.2700

5.7319

4.6476

3.8625

3.2785

1.7804

1.1424

0.7704

October 1, 2016

38.9155

28.2163

21.7685

16.8691

13.1552

10.3440

8.2168

5.3827

3.7377

2.7609

2.1605

1.7742

1.5119

0.8895

0.6002

0.4132

October 1, 2017

38.9155

24.1277

13.1386

3.6148

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

The exact stock prices and effective dates may not be as set forth in the table above, in which case:

·      If the stock price is between two stock prices in the table or the effective date is between two effective dates in the table, the number of additional shares will be determined by a straight line interpolation between the number of additional shares set forth for the higher and lower stock prices and the earlier and later effective dates, as applicable, based on a 365 day year.

·      If the stock price is greater than $30.00 per share (subject to adjustment in the same manner as the stock prices set forth in the column headings in the table above), no additional shares will be added to the conversion rate.

·      If the stock price is less than $5.93 per share (subject to adjustment in the same manner as the stock prices set forth in the column headings of the table above), no additional shares will be added to the conversion rate.

Notwithstanding the foregoing, in no event will the conversion rate exceed 168.6340 shares of common stock per $1,000 principal amount of Notes, subject to adjustment in the same manner as the conversion rate as set forth under “Description of the Notes—Conversion Rate Adjustments” in the Preliminary Prospectus Supplement.

CUSIP/ISIN:

36191U AA4 / US36191UAA43

Joint Book-Running Managers:

UBS Investment Bank

BofA Merrill Lynch

Credit Suisse

Joint Lead Manager:

RBS

Co-Manager:

Santander