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CUSIP665162863
Inception Date4/01/94
Total Net Assets$1,423,192,989 (as of 08/31/19)
YTD Total Return6.85% (as of 09/20/19)
Distribution Rate*2.98% (as of 09/20/19)
Tax-Equivalent Distribution Rate*4.59% (as of 09/20/19)
30-Day SEC Yield w/ Waivers*2.49% (as of 08/31/19)
30-Day SEC Yield w/o Waivers*2.47% (as of 08/31/19)
Tax-Equivalent 30-Day SEC Yield*4.21% (as of 08/31/19)
*Distribution rate and tax-equivalent distribution rate represent the annualization of the Fund's distributions for the prior month ending on the date shown, including capital gain distributions. The 30-day SEC yield w/waivers represents the annualization of the Fund's net investment income, excluding capital gain income and includes contractual expense reimbursements. It would be lower without those reimbursements. The 30-day SEC yield w/o waivers represents the annualization of the Fund's net investment income, excluding capital gain income, but excludes contractual expense reimbursements, resulting in a lower yield. The tax-equivalent 30-day SEC yield represents the annualization of the Fund's net investment income, excluding capital gain income. The tax-equivalent distribution rate and tax-equivalent 30-day SEC yield are based on an assumed tax rate of 45.3% for Arizona, 54.1% for California and 40.8% for national municipal funds.
Total ReturnsTotal Returns for Month Ending 08/31/19
Performance quoted represents past performance and does not guarantee future results. Investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than that shown here.

Northern Trust Investments, Inc. has contractually agreed to reimburse a portion of the operating expenses of the Fund (other than certain excepted expenses, i.e., acquired fund fees and expenses; the compensation paid to each Independent Trustee of the Trust; expenses of third party consultants engaged by the Board of Trustees; membership dues paid to the Investment Company Institute and Mutual Fund Directors Forum; expenses in connection with the negotiation and renewal of the revolving credit facility; and extraordinary expense and interest) to the extent the "Total Annual Fund Operating Expenses" exceed 0.45%.The "Total Annual Fund Operating Expenses After Expense Reimbursement" may be higher than the contractual limitation as a result of the excepted expenses, including but not limited to acquired fund fees and expenses, that are not reimbursed. This contractual limitation may not be terminated before July 31, 2020 without the approval of the Board of Trustees. In the absence of fee waivers, yield, total return, growth since inception and dividends would have been reduced. Total return is based on net change in NAV assuming reinvestment of distributions.
Annual Expense Ratios 
 Gross Expense RatioNet Expense Ratio
Tax-Exempt0.50%0.46%
Includes contractual expense reimbursements that, if not extended, will end on July 31, 2020. The Fund also includes voluntary expense reimbursements that may change or end at any time.
Calendar Year Returns 
       2018      2017      2016      2015      2014
Tax-Exempt0.65%4.83%0.40%3.69%10.47%
Bloomberg Barclays U.S. Municipal Index1.28%5.45%0.25%3.30%9.05%
Morningstar Category Avg. Muni National Long0.27%5.71%0.00%3.07%10.58%
Performance quoted represents past performance and does not guarantee future results.
As of 07/31/19
As of 07/31/19
As of 07/31/19
Fund CharacteristicsAs of 07/31/19
All data is as of date indicated and subject to change.
Bond Risk: Bond funds will tend to experience smaller fluctuations in value than stock funds. However, investors in any bond fund should anticipate fluctuations in price, especially for longer-term issues and in environments of rising interest rates.
Characteristics: Benchmark and Fund analytics have been calculated using a third party vended model. All material has been obtained from sources believed to be reliable, but the accuracy, completeness and interpretation cannot be guaranteed. Information contained herein is current as of the date appearing in this material only and is subject to change without notice. Certain benchmark calculations may not match the published benchmark characteristics.
Tax-Free/AMT Risk: Tax-exempt funds’ income may be subject to certain state and local taxes and, depending on your tax status, the federal alternative minimum tax.
Bloomberg Barclays U.S. Municipal Index is an unmanaged index of investment grade (Baa3 or better) tax-exempt bonds with a remaining maturity of at least one year. It is not possible to invest directly in an index.
Quality Distribution: Credit quality ratings are based on Moody’s, Standard & Poors and Fitch ratings. If ratings from all three rating agencies disagree, the security is assigned the middle rating. If two of the three agree, the security is assigned the rating from those two. If none of these three rating agencies has assigned a rating, the Fund will assign a rating of not rated. The ratings, expressed in Standard & Poors nomenclature, range from AAA (extremely strong capacity to meet its financial commitment) to D (in default). Short-term ratings, when applicable, are expressed in Standard & Poors nomenclature, range from A-1 (obligors capacity to meet its financial commitment on the obligation is strong) to A-3 (exhibits adequate protection parameters). Cash Equivalents includes any traded cash (forward settling trades), the sweep vehicle and other short term instruments. The ratings represent the rating agencies opinions of the quality of the securities they rate. Ratings are relative and subjective and are not absolute standards of quality.
Distribution Calculations: All distribution calculations (Maturity Distribution, Sector Weightings and Quality Distribution) are measured on a trade date basis and are adjusted for uninvested cash from the market value used to compute the percentage calculations.