Exhibit (g)(15)
June 12, 2026
State Street Bank and Trust Company
1 Iron Street
Boston, MA 02210
Attention: Suzanne M. Hinckley, SVP
Re: Calamos ETF Trust and Calamos Advisors Trust (the “Funds”)
Ladies and Gentlemen:
Please be advised that the undersigned Funds have been incorporated and registered as a management investment company under the Investment Company Act of 1940, as amended, and such Funds have established those new series of shares identified under its name on Exhibit A hereto (each, a “Portfolio”).
In accordance with Section 19.6, the Additional Portfolios provision, of the Master Custodian Agreement dated as of September 11, 2009, as amended, modified, or supplemented from time to time (the “Agreement”), by and among each registered investment company party thereto, and State Street Bank and Trust Company (“State Street”), the undersigned Funds, on behalf of their respective Portfolios, hereby requests that State Street act as Custodian for the Portfolios under the terms of the Agreement, and that Appendix A to the Agreement is hereby amended and restated as set forth on Exhibit B attached hereto. In connection with such request, each undersigned Fund hereby confirms, as of the date hereof, its representations and warranties set forth in Section 19.7 of the Agreement.
Please indicate your acceptance of the foregoing by executing this letter agreement and returning a copy to the Funds.
Sincerely,
CALAMOS ETF TRUST
on behalf of:
| Calamos Active Hedged Equity ETF | ||
| Calamos Timpani Active SMID Growth ETF | ||
| By: | /s/ Stephen Atkins | |
| Name: | Stephen Atkins | |
| Title: | Treasurer, Duly Authorized | |
CALAMOS ADVISORS TRUST
on behalf of:
| Calamos U.S. Equity Autocallable VIP Fund | ||
| By: | /s/ Stephen Atkins | |
| Name: | Stephen Atkins | |
| Title: | Treasurer, Duly Authorized | |
Information Classification: Limited Access
Agreed and Accepted:
STATE STREET BANK AND TRUST COMPANY
| By: | /s/ Suzanne M. Hinckley | |
| Name: | Suzanne M. Hinckley | |
| Title: | SVP | |
| Effective Date: | ||
Information Classification: Limited Access
EXHIBIT A
CALAMOS ETF TRUST
on behalf of:
Calamos Active Hedged Equity ETF
Calamos Timpani Active SMID Growth ETF
CALAMOS ADVISORS TRUST
on behalf of:
Calamos U.S. Equity Autocallable VIP Fund
Information Classification: Limited Access
EXHIBIT B
APPENDIX A
TO
MASTER CUSTODIAN AGREEMENT
MANAGEMENT INVESTMENT COMPANIES REGISTERED WITH THE SEC AND PORTFOLIOS THEREOF, IF ANY
| CALAMOS ADVISORS TRUST | ||
| Calamos Growth and Income Portfolio | 36-7271106 | |
| Calamos U.S. Equity Autocallable VIP Fund | [to come] | |
| CALAMOS ETF TRUST | ||
| Calamos Antetokounmpo Global Sustainable Equities ETF | 88-4166679 | |
| Calamos Convertible Equity Alternative ETF | 93-1403228 | |
| Calamos CEF Income & Arbitrage ETF | 93-3384806 | |
| Calamos Nasdaq Equity & Income ETF | 93-4047483 | |
| Calamos S&P 500 Structured Alt Protection ETF – May | 99-1891857 | |
| Calamos S&P 500 Structured Alt Protection ETF – July | 99-2036587 | |
| Calamos S&P 500 Structured Alt Protection ETF – August | 99-2010412 | |
| Calamos Nasdaq-100 Structured Alt Protection ETF – June | 99-2246961 | |
| Calamos Russell 2000 Structured Alt Protection ETF – July | 99-3084638 | |
| Calamos Nasdaq-100 Structured Alt Protection ETF – September | 99-2264630 | |
| Calamos S&P 500 Structured Alt Protection ETF – September | 99-2059476 | |
| Calamos Laddered S&P 500 Structured Alt Protection ETF | 99-4100530 | |
| Calamos S&P 500 Structured Alt Protection ETF – October | 99-4151647 | |
| Calamos Russell 2000 Structured Alt Protection ETF – October | 99-3099426 | |
| Calamos Nasdaq-100 Structured Alt Protection ETF – December | 99-2309567 | |
| Calamos S&P 500 Structured Alt Protection ETF – November | 99-4183246 | |
| Calamos Nasdaq-100 Structured Alt Protection – March | 99-2360298 | |
| Calamos Russell 2000 Structured Alt Protection ETF – January | 99-3170084 | |
| Calamos S&P 500 Structured Alt Protection ETF - December | 99-4213949 | |
| Calamos S&P 500 Structured Alt Protection ETF – April | 99-4289511 | |
| Calamos S&P 500 Structured Alt Protection ETF – June | 99-4312375 | |
| Calamos S&P 500 Structured Alt Protection ETF – January | 99-4237715 | |
| Calamos S&P 500 Structured Alt Protection ETF – February | 99-4254967 | |
| Calamos S&P 500 Structured Alt Protection ETF – March | 99-4278288 | |
| Calamos Russell 2000 Structured Alt Protection ETF – April | 99-3193460 | |
| Calamos Bitcoin Structured Alt Protection ETF – January | 33-2314879 | |
| Calamos Bitcoin 90 Series Structured Alt Protection ETF – January | 33-2217288 | |
| Calamos Bitcoin 80 Series Structured Alt Protection ETF – January | 33-2187566 | |
| Calamos Bitcoin Structured Alt Protection ETF – January Sub 1 | 98-1828163 | |
| Calamos Bitcoin 90 Series Structured Alt Protection ETF – January Sub 1 | 98-1829852 | |
| Calamos Bitcoin 80 Series Structured Alt Protection ETF – January Sub 1 | 98-1830164 | |
| Calamos Bitcoin 90 Series Structured Alt Protection ETF® – April | 33-2463234 | |
| Calamos Bitcoin 80 Series Structured Alt Protection ETF® - April | 33-2482672 | |
| Calamos Bitcoin Structured Alt Protection ETF® – April | 33-2383221 | |
| Calamos Bitcoin 90 Series Structured Alt Protection ETF – April Sub 1 | 98-1841159 | |
Information Classification: Limited Access
| EXHIBIT B | ||
| Calamos Bitcoin 80 Series Structured Alt Protection ETF - April Sub 1 | 98-1841818 | |
| Calamos Bitcoin Structured Alt Protection ETF – April Sub 1 | 98-1840947 | |
| Calamos Autocallable Income ETF | 33-5015390 | |
| Calamos Autocallable Income ETF – Sub 1 | 98-1862415 | |
| Calamos Bitcoin Structured Alt Protection ETF® – July | 33-2414289 | |
| Calamos Bitcoin 90 Series Structured Alt Protection ETF® – July | 33-2754251 | |
| Calamos Bitcoin 80 Series Structured Alt Protection ETF® – July | 33-2772412 | |
| Calamos Bitcoin Structured Alt Protection ETF – July Sub 1 | 98-1863716 | |
| Calamos Bitcoin 90 Series Structured Alt Protection ETF – July Sub 1 | 98-1863347 | |
| Calamos Bitcoin 80 Series Structured Alt Protection ETF – July Sub 1 | 98-1862860 | |
| Calamos Bitcoin Structured Alt Protection ETF® – October | 33-2442769 | |
| Calamos Bitcoin 90 Series Structured Alt Protection ETF® – October | 33-2815363 | |
| Calamos Bitcoin 80 Series Structured Alt Protection ETF® – October | 33-2844374 | |
| Calamos Laddered Bitcoin Structured Alt Protection ETF® | 39-3576968 | |
| Calamos Laddered Bitcoin 90 Series Structured Alt Protection ETF® | 39-3590811 | |
| Calamos Laddered Bitcoin 80 Series Structured Alt Protection ETF® | 39-3618434 | |
| Calamos Bitcoin Structured Alt Protection ETF - October Sub 1 | 98-1881335 | |
| Calamos Bitcoin 80 Series Structured Alt Protection ETF – October Sub 1 | 98-1883173 | |
| Calamos Bitcoin 90 Series Structured Alt Protection ETF – October Sub 1 | 98-1882286 | |
| Calamos Nasdaq Autocallable Income ETF | 39-4204450 | |
| Calamos Nasdaq Autocallable Income ETF – Sub 1 | 98-1829554 | |
| Calamos Autocallable Growth ETF | 41-4089778 | |
| Calamos Tax-Aware Collateral ETF | 41-4113573 | |
| Calamos Active Hedged Equity ETF | [to come] | |
| Calamos Timpani Active SMID Growth ETF | 42-2268393 | |
| CALAMOS INVESTMENT TRUST | ||
| Calamos Convertible Fund | 36-3316238 | |
| Calamos Evolving World Growth Fund | 26-2192228 | |
| Calamos Global Convertible Fund | 47-2271491 | |
| Calamos Global Equity Fund | 20-8166626 | |
| Calamos Global Opportunities Fund | 36-4088206 | |
| Calamos Growth Fund | 36-3723359 | |
| Calamos Growth and Income Fund | 36-3575418 | |
| Calamos Hedged Equity Fund | 47-2255361 | |
| Calamos High Income Opportunities Fund | 36-4307069 | |
| Calamos International Growth Fund | 20-2395043 | |
| Calamos Market Neutral Income Fund | 36-3723358 | |
| Calamos Select Fund | 22-3848966 | |
| Calamos Phineus Long/Short Fund | 47-5668954 | |
| Calamos Total Return Bond Fund | 20-8872705 | |
| Calamos Short-Term Bond Fund | 83-0775729 | |
| Calamos Timpani Small Cap Growth Fund | 83-3325222 | |
| Calamos Timpani SMID Growth Fund | 83-4647954 | |
| Calamos International Small Cap Growth Fund | 87-4563290 | |
| Calamos Merger Arbitrage Fund | 93-1422103 | |
Information Classification: Limited Access
| CALAMOS ANTETOKOUNMPO SUSTAINABLE EQUITIES TRUST | ||
| Calamos Antetokounmpo Sustainable Equities Fund | 88-3877464 | |
| CALAMOS CONVERTIBLE OPPORTUNITIES AND INCOME FUND | 03-0426532 | |
| CALAMOS CONVERTIBLE AND HIGH INCOME FUND | 02-0683363 | |
| CALAMOS STRATEGIC TOTAL RETURN FUND | 04-3785941 | |
| CALAMOS GLOBAL TOTAL RETURN FUND | 20-3377281 | |
| CALAMOS GLOBAL DYNAMIC INCOME FUND | 20-8819776 | |
| CALAMOS DYNAMIC CONVERTIBLE AND INCOME FUND | 47-1549409 | |
| CALAMOS LONG/SHORT EQUITY& DYNAMIC INCOME TRUST | 82-2860404 | |
Information Classification: Limited Access