Mr. Igor Gonzales reports

SIERRA METALS ANNOUNCES FILING OF NI 43-101 TECHNICAL REPORT ON THE BOLIVAR MINE IN MEXICO

Sierra Metals Inc. has filed a technical report prepared in accordance with National Instrument 43-101 on the Bolivar mine. The report supports the disclosure made by the company in its news release dated May 22, 2018, entitled "Sierra Metals Increases Mineral Reserve Estimate by 83% for its Bolivar Mine, Mexico." There are no material differences in the mineral resources and reserves contained in the report from those disclosed in the May 22, 2018, news release.

The report includes mineral resources and reserves for the Bolivar mine with:

• Total probable mineral reserves for Bolivar are 7,925,000 tonnes averaging 18.9 grams per tonne silver, 0.86 per cent copper and 0.25 g/t gold, and 1.14 per cent copper equivalent, representing an 83-per-cent increase to the previous probable mineral reserve estimate.
• Total indicated mineral resources for Bolivar are 13,267,000 tonnes averaging 22.5 g/t silver, 1.04 per cent copper and 0.29 g/t gold, and 1.36 per cent CuEq, representing a 42-per-cent increase to the previous indicated mineral resource estimate.
• Total inferred mineral resources for Bolivar are 8,012,000 tonnes averaging 22.4 g/t silver, 0.96 per cent copper and 0.42 g/t gold, and 1.35 per cent CuEq, representing an 11.5-per-cent decrease to the previous inferred mineral resource estimate.
• The updated resource and reserve estimate varies from the February, 2017, technical report due to a variety of factors, including: a 24-per-cent increase in copper price assumptions*, notable increases in metallurgical recovery assumptions*, an increase in the net smelter return (NSR) cut-off grades resulting in higher-value material, change in commodity prices* and depletion by production since the report was completed.
• The updated resource and reserve estimate has incorporated new exploration drilling, sampling and face mapping information into the geologic interpretation and grade estimations providing more refined resource models.

* Metal price assumptions considered for the calculation of unit values are: copper (Cu): $3 (U.S.) per pound, silver (Ag): $18.25 (U.S.) per ounce and gold (Au): $1,291 (U.S.) per ounce. Metallurgical recovery assumptions are based on actual plant data for 2017 to 2018 and are 78 per cent Ag, 83 per cent Cu and 64 per cent Au.

The report dated June 28, 2018, with an effective date of Oct. 31, 2017, is entitled "NI 43-101 technical Report on Resources and Reserves, Bolivar Mine, Mexico," and was prepared by independent SRK Consulting (U.S.) Inc.

Signed by qualified persons:

• Giovanny Ortiz, BSc, PGeo, FAusIMM, associate resource geologist;
• Shannon L. Rheaume, BASc, mining and mineral processing, PEng, senior mining engineer;
• Jeff Osborn, BEng, mining, MMSAQP, principal mining engineer;
• Daniel H. Sepulveda, BSc, SME-RM, metallurgist;
• John Tinucci, PhD, PE, president/practice leader/principal geotechnical engineer;
• Mark Willow, MSc, CEM, SME-RM, principal environmental scientist.

Notes on the resource and reserve estimate

The procedures and methods supporting the mineral resource and reserve estimation have been developed in conjunction with Dia Bras geological personnel. The understanding of the geology and mineralization at Bolivar is based on a large volume of geologic data, as well as a robust history of production. SRK has reviewed the methods and procedures for data collection methods supporting the estimate, and notes that they are reasonable and consistent with industry best practice. Geology models were generated by Dia Bras geologists using Leapfrog Geo, and locally vary significantly from those used in previous reports. A combination of diamond drilling, channel sampling and mine mapping has been used to inform these models, and SRK is of the opinion that they are an accurate interpretation of the mineralization at Bolivar. These models, presented as 3-D wire frames, are used to constrain block models, which are flagged with variables, such as bulk density, mine area and depletion.

The resource and reserve estimations presented herein have been conducted or reviewed by independent consultants using supporting data generated by the site. SRK conducted independent estimations for the Bolivar mine. Grade for the three primary commodities (copper, silver and gold) is estimated into the block models using both drilling and channel samples, applying industry-standard estimation methodology. Interpolation methods were generally through ordinary krigging. Mineral resources and reserves estimated by the independent consultants are categorized in a manner consistent with industry best practice, and are reported above reasonable unit value cut-offs based on actual marginal production costs to satisfy public reporting criteria.

SRK is of the opinion that the resource and reserve estimations are suitable for public reporting and are a fair representation of the in situ contained metal for the Bolivar deposit.

The information in this announcement regarding the resource and reserve estimate included in the report is qualified in its entirety by reference to the report. The report is available for review on SEDAR, EDGAR and the company's website.

Quality control

The technical content of this news release has been reviewed and approved by the following.

• Gordon Babcock, PEng, chief operating officer and a qualified person under National Instrument 43-101 (Standards of Disclosure for Mineral Projects);
• Americo Zuzunaga, MAusIMM CP (mining engineer), vice-president of corporate planning, a qualified person, a chartered professional qualifying as a competent person under the Joint Ore Reserves Committee (JORC) Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves;
• Augusto Chung, FAusIMM CP (metallurgist), consultant to Sierra Metals, a qualified person, a chartered professional qualifying as a competent person on metallurgical processes.

About Sierra Metals Inc.

Sierra Metals is a Canadian-based expanding polymetallic mining company with production from its Yauricocha mine in Peru, and its Bolivar and Cusi mines in Mexico. The company is focused on increasing production volume and increasing mineral resources. Sierra Metals has recently had several new key discoveries and still has many more exciting brownfield exploration opportunities at all three mines in Peru and Mexico that are within close proximity to the existing mines. Additionally, the company also has large land packages at all three mines with several prospective regional targets providing longer-term exploration upside and mineral resource growth potential.

We seek Safe Harbor.